Adjustable Stand-or-Sit Wood Lathe Standmnwoodturners.com/cms-files/sit-or-stand-lathe-stand...1 Adjustable Stand-or-Sit Wood Lathe Stand Stand Design and Fabrication by Mark K. Debe*,

1

Adjustable Stand-or-Sit Wood Lathe StandStand Design and Fabrication by

Mark K. Debe*, [email protected] CAD Drawings by

Tom Kindom*, [email protected]

*Members of The Minnesota Woodturners Association October, 2015

Lathe Stand in Sitting Position Lathe Stand in Standing Position

2Mark K. Debe - Adjustable Stand-or-Sit Wood Lathe Stand- [email protected], October, 2015

ContentsSlide #

• Introduction ……………………………………………. 3 • Lathe stand physical characteristics………………… 4 • Design criteria and constraints………………………. 5 • Drawings of subassemblies and component parts… 6 • Directions for changing from standing-to-sitting

configuration…………………………………………….. 29 • Directions for changing from sitting-to-standing

configuration…………………………………………….. 31 • Finding the center of gravity of the lathe

and carriage assembly ……………………………….. 32 • Fabrication process, assembly comments………….. 34

3

IntroductionThe motivation for designing and fabricating an adjustable wood lathe stand was to enable any MWA (Minnesota Woodturners Association) member to take the wood-turning classes our club offers, while confined to a wheelchair or sitting position. Previously this was not possible. Since the lathe would have to be used for every such class, it was desirable to make the stand configurable for either a sitting or standing position and be safely and easily convertible from one configuration to the other while the lathe was mounted on the stand. My personal interest in this idea was sparked while attending the 2014 AAW meeting in Phoenix, where a commercially available sit-down lathe was exhibited, but did not appear to be adjustable or wide enough for a wheelchair and was quite expensive.

A midi-sized lathe, e.g. a Delta 46-460, or Jet JWL 1221, would be about the largest lathe size such a stand would need to accommodate for use in our club classes. Anything much heavier than the approximately 100 lb. weight of such midi-lathes would also require a proportionately heavier and costlier stand, and present additional safety issues. So the design and fabrication of this stand as presented in the following slides is limited to such midi-sized lathes. But certainly if the reader is interested, any modifications are possible to make it more robust while still taking advantage of some of the incorporated design principles, such as alignment of the center-of-gravity of the lathe and carriage it sits on with the intersection point of the rotational and lift axes.

This lathe stand as designed and built is rightly a prototype. The final design I chose to fabricate was my fifth design iteration on paper, with each such design getting simpler, lighter, more stable, cheaper and above all safer to operate. The actual design discussed below has proven to work well, with adequate stability, good balance in both configurations, and sufficient wheel chair accessibility while requiring only a single person to convert the stand plus lathe between standing and sitting configurations. There are no doubt a large number of variations in the design and component details that could be implemented while achieving a similar result, and anyone skilled in the art of mechanical design and welding could apply their own chosen variations. To control costs, I used and searched for steel available from discount yards reselling surplus structural steel. Often then my choice of a particular structural member of the stand was chosen for what I found available for $1.50/lb. on that day, but a tubing or angle of another dimension or cross-section could be made to work just as well. We have chosen to reproduce the drawings for the lathe stand subassemblies and components actually used as precisely as we could in order to give a baseline starting point to anyone wanting to build their own stand or a stand for their club, with some assurance it would work properly. My estimate of my total materials and parts cost, from bulk steel to spray paint is somewhere between $300 and $350, with all the metal parts fabrication and welding done using my own equipment. If the required metal cut-off saws, large drill bits, grinders and welding units are not available, then the costs could be considerably higher to get the parts fabricated and subassemblies welded. I have chosen to retain ownership of the lathe stand but donate its use to our club for as long as it is useful, with responsibility for maintaining it and fixing it should anything go wrong.

I am particularly grateful to Tom Kindom, who not only was the first wheelchair user and evaluator of the lathe stand, but also the skilled techie who converted my hand-drafted drawings into Fusion 360 CAD figures so they would be intelligible to other humans. He also provided key design constraints on height of the turning-axis above the floor and approach-width for comfortable access to the lathe in his wheelchair. His assessment of the performance of the lathe stand was critical for its functional evaluation, concluding that although it was a prototype, no significant design modifications were required. We are especially grateful to the AAW for a $500 educational opportunity grant that enabled the CAD figures to be produced and hereby made available to anyone wishing to build their own stand.

Mark K. Debe, Stillwater, MN - Oct. 23, 2015 Treasurer, Minnesota Woodturners Association

Mark K. Debe - Adjustable Stand-or-Sit Wood Lathe Stand- [email protected], October, 2015

4

Lathe Stand Physical Characteristics• Stand consists of two basic subassemblies: a rotating/translating Carriage subassembly and a fixed Leg stand subassembly. • The lathe is bolted to the carriage and the combined assembly rotates about 1 inch dia. pivot bolts in the leg stand subassembly. • Total weight of the stand without the lathe: 108.4 pounds. Combined weight of the stand and Delta 46-460 lathe: 205 pounds. • Size of lathes it can accommodate as designed: Any midi or mini-sized lathe not exceeding 150 lb. or 32 inches in length. • Front side clearance width for rotational access by wheelchairs: 44 inches • Number and angles of tilted configurations: Two, at 22.5 and 45 degrees • Horizontal displacement of turning axis towards the turner between standing and sitting configurations: 7.5 inches • Vertical drop of the turning axis between standing and lowest sitting configurations: 9 inches • Height of turning axis above the floor when in full tilted configuration: 36.5 inches • Height of turning axis above the floor when in the standing configuration: 45.5 inches • Transport means: Wheels on rear of stand legs and lift handles on front top of stand • Tool storage during use: vertically, in lift handles

Carriage subassembly

Pivot bolt standing

Jack and drill attachment

Leg stand subassembly

Pivot axis sitting

Rear Wheels

Locking bolt

Wooden roller guide and bolt


Tool storage

Pivot bolt sitting

5

Design Criteria and Constraints

• The approachable width of the stand between its vertical legs or horizontal members must be adequate for a wheelchair to move forward and pivot if needed in order to back out.

• In the sitting position the lathe turning axis should be lowered and rotated forward so as to allow adequate clearance above the knees of the sitting operator, e.g. for a knee-height above the floor of 27 inches. This would be variable depending on the individual and sitting height of their chair.

• The stand plus lathe should be easily moveable across the floor by one person without back strain. • The carriage plus lathe subassembly must move both vertically and rotationally when transitioning between

standing and sitting configurations, and be under balance, captive control at all times for safe operation. • A human applied force of no more than a few pounds should be needed at any time in transitioning the

lathe stand between its sitting and standing configurations. • The carriage-plus-lathe subassembly must be balanced with respect to rotation about the carriage pivot

bolts so that no significant torques are required to safely hand-rotate the carriage and lathe. This requires that the carriage-plus-lathe subassembly's center-of-gravity be co-linear with the carriage pivot bolts’ axis.

• To safely lift or lower the combined weight of the lathe and carriage, a scissor jack or its equivalent will be operated by a hand-held electric drill. Vertical movement and rotational movements are to be kept independent so the carriage and lathe are at all time constrained from falling or tilting uncontrollably.

• The carriage-plus-lathe subassembly must be balanced with respect to vertical movement when transitioning between sitting and standing configurations. This requires that the carriage-plus-lathe subassembly's center-of-gravity lie on the jack lift-axis. This avoids “racking” of the carriage when moving vertically between the sitting and standing configurations.


6

Drawings of subassemblies and component parts

Slides 8 - 28 show the drawings for the complete assembly weldment, subassembly weldments and component parts drawings. All dimensions are in inches. Where dimensions are expressed to three decimal places but correspond to an exact fractional dimension, such as 0.437 ~ 7/16”, the expectation is that the + 1/64” is sufficient precision. In the few places where greater precision is needed it is discussed in connection to the part description below.

Slides 8,9: Overviews of the lathe stand final assembly and leg stand subassembly, with quantity and number of parts identified. Slide 10: Vertical legs of the stand, made from steel tubing with rectangular cross section. Three sixteenths inch wall thickness is sufficient to reduce weight but maintain high level of rigidity. The small 0.070” thick rectangular welded plates are to give beefier wall thickness where the carriage locking bolts slip through, as well as providing a clamping surface for the ⅜ inch locking bolts that go through the carriage end plates and stand’s vertical legs at this point without warping either of these. Slide 11: The end caps are primarily cosmetic but will keep wood chips and spider webs out of the inside of the leg tubes. Slide 12: The metal struts are prefabricated 10’ long products sold at DIY stores for use as electric cable-run supports. They were used simply because I had some leftover pieces from another project, so any type of handle could be substituted. But it was convenient to use in that it already had perforations for potential use as tool racks and it welds very nicely. With the rear leg wheels lowered, only a moderate lift force is needed to scoot the lathe and stand around the shop floor. Slide 13: These small welded brackets are really safety features. When changing from a sitting to a standing configuration or vice versa, they prevent the carriage and lathe assembly from rotating or falling backward from in-between the vertical leg members. Their length and shape is not critical, just so that they can act as vertical guides and limit the backward rotation. Slide 14: The carriage roller brackets and wooden rollers/bolts (see slide 4) serve a similar purpose to guide the carriage and lathe assembly up and down safely during a transition when the carriage is not fixed to the vertical leg members by pivot or locking bolts. The wooden roller was made from a 4 inch long piece of 1 inch dowel with a ⅜ inch center hole for the ⅜” bolt down its center that tightens onto the roller bracket. Slide 15: The jack plates are simply square plates that clamp on each side of the jack’s base to the top of the I-beam. Each one is secured to the I-beam with ½-20 bolts, nuts and lock washers. Slide 16: The bronze bushings were the most costly single pre-made item purchased. Each vertical leg contains four of them for a total of eight at about $ 5 each, purchased on-line. They slip into holes in the vertical legs to locate the 1 inch diameter pivot bolts that support the carriage. They were chosen so these large bolts have more surface area of support than just the thin wall of the leg tubing and more importantly to eliminate metal galling over time that would hinder the carriage rotation. They are not braised or permanently fixed to the vertical legs, but are lightly press fit into the PVC bushings described in slide 17. Slide 17: These PVC bushings were simply a cheap and easy way to keep the bronze bushings from falling out of the pivot holes of the legs whenever that hole configuration is not being used. I found some easy-to-convert parts in the plumbing supply aisle of a home supply-DIY store, i.e. typical 1-¼” sink plumbing hardware. To install them in the vertical legs with the bronze bushings, they were held in place by their circumference with a large pair of pliers through the opening in the top end of the vertical legs. This is why there is a wooden cap on the top of the steel tubing legs rather than a welded end cap, so that access to the bushings remains an option for any repair. The PVC bushings bear no load. I used some silicone adhesive to hold the bronze bushings inside the PVC bushings too. Slide 18: The jack-to-pipe connector was made to allow coupling of the steel pipe that raises and lowers the carriage to the jack, but be removable and free from slippage or movement at the same time. I had to open the steel crimp-ears on the scissor jack’s top as it was made, so that this 1” wide, ¼” thick plate would slip under the ears. Then I bent them back. This holds the jack-to-pipe connector firmly in place on the jack top at all times, while the pipe slips over or off the 1” diameter rod stub welded to the the center of the ¼” plate. A clearer photo of the connector is shown in the left photo on slide 30. Slides 19 and 20: The 1” diameter class 8 steel bolts used as the pivot axes for the carriage. The bolts slip easily into the bronze bushings and the large washer goes onto the bolt before inserting it through the holes in the vertical legs. Large washers are used under the nuts as well. The flanges of the bronze bushings serve as the “slip gaskets” between the vertical steel legs and the carriage end brackets.


7

Drawings of subassemblies and component parts - continued

Slide 21: Overview of the carriage weldment subassembly, with quantity and number of parts identified. Note that the bolt hole pattern in the carriage bottom plates, for bolting the lathe to the carriage, are not centered front to back. This is because the center-of-gravity of the lathe plus carriage is aligned with the long symmetry axis of the carriage or pivot axis. This shifts the lathe’s position on the carriage towards the front by 0.5 inches for the Delta 46-460 midi-lathe, for which the four bolt holes were patterned. Slides 22 - 24: These show the component parts of the carriage end brackets. The two brackets must be made as identical as possible, or at least the pivot holes and locking bolt holes must be aligned to within 0.005”. It is recommended to make the end plates first and drill the center holes in both plates as the same time. Slide 25: The steel angles that connect the two carriage end-brackets together have to be carefully cut to the exact same length and welded so that the carriage end plates are highly parallel to each other. This is because they must rotate between the vertical stand legs without rubbing the small reinforcement plates on the legs where the locking bolts go through the legs. There will only be a few thousands of an inch of clearance so that when the ⅜-16 inch locking bolts are tightened they clamp the carriage end plates to the stand vertical legs without deforming either one of the latter. Slide 26: The carriage plate gussets are an example of steel surplus plates bought at the discount steel supply source for $1 each. They could be any shape but these were just sized right for this application. Slide 27: The carriage lifting plate is self explanatory and serves to couple the top of the jack lifting pipe to the carriage in a way that can not possibly slip during the operation, but is still easily removable when changing configurations. The 1 inch diameter stub welded to the plate center should slip loosely inside the pipe inner diameter. The welding of this carriage lifting plate to the underside of the carriage angle rails should be done at the very end of the assembly of the carriage, once the entire stand is built and the lathe can be bolted to the carriage. This is so that the jack and its lifting tube can be oriented exactly straight up and down while attached to the carriage lifting plate, and all three items moved slightly left or right, to within 1/16 of an inch, to keep the carriage assembly balanced on the top of the pipe. Once this balance point is found, the lifting plate can be tack welded in place and then the carriage removed for complete welding. This balance is critical so that when the carriage and lathe assembly is translating vertically between the sitting and standing positions, it will not “rack” or bind on the inner sides of the vertical legs. Note on slides 32-33 I discuss finding the center-of-gravity of the lathe, carriage and combined assembly, and from that the calculated position of where the lifting plate should be located on the steel angles. The above suggestion of tack welding the lifting plate after moving it slightly if needed to get a good balance around the calculated position is a refinement. Slide 28: Finally, the I-beam. The length of this member, expressed as the digital version of 45-15/16 inches, is critical so that the vertical legs are spaced exactly by the right amount for clearance of the carriage assembly between the stand’s vertical legs at the welded plate positions where the locking bolts go through. This length should be kept to within 1/64th of an inch with errors on the under side. The choice of an I-beam cross-section for this horizontal member of the stand is not critical from simply a strength standpoint, but it does have an important bearing on the stability of the whole stand in a way I did not anticipate. The I-beam twists more easily about its long axis than a steel tube of some open cross-section would, due to a torque about that axis. If the lathe and stand are sitting on an uneven floor, and the carriage pivot and locking bolts are loose, the weighted moments of the stand and lathe produce a torque about the I-beam’s long axis causing it to twist slightly. When the locking and pivot bolts are then tightened, the net result is that all four of the stand’s feet will be on the floor and it will appear more stable against vibrations from an asymmetric turning piece of wood. However if the twist is too much, the locking bolt holes of the carriage end plates will misalign with the corresponding holes in the stand’s vertical legs, making it difficult to get them through the sets of holes. Since the locking bolt is ⅜” diameter and the hole 7/16” diameter, it doesn’t take much misalignment to give binding of the bolts. The screw-on feet on the stand’s horizontal legs need to be adjusted then. This natural torquing of the I-beam also means, however, that during welding of the I-beam to the stand assembly, it is critical that the vertical legs be maintained exactly parallel in both vertical planes.


8

PARTS LISTDESCRIPTIONPART NUMBERQTYITEM

Lathe Stand Sub Assy Weldment

11

Carriage end weldment12Hex Flange Bolt3/8-16 x 4.0023Hex Flange Nut3/8 - 1624 Wood Cap25 Wood Roller26 Jack Plate27Larin# SJ-1 1.5 TonJack18 Jack to Pipe connector19Steel Pipe 8.25 Long x 1.0 ID 1.12 OD

Jack Pipe110

1

1

2

2

3

3

4

4

A A

B B

C C

D D

SHEET 1 OF 1

DRAWN

CHECKED

QA

MFG

APPROVED

One 10/19/2015

DWG NO

Lathe Stand Assembly Final

TITLE

SIZE

CSCALE

REV

1

2

10

8

7

5

3

3

Lathe StandAssembly Final

StrangeWorks EngineeringMpls, MN 55432 763-219-1988

4

6

9


9

SECTION A-ASCALE 1 / 8

VIEW C-CSCALE 1 / 4

PARTS LIST

DESCRIPTIONPART NUMBERQTYITEM Horz. Stand Leg21 Vert. Stand Leg22 I Beam13 Plate for feet44 Feet45 Bushing Bronze86 PVC Bushing47 Lifting Arm28 Leg cover plate49 Large Bolt210 Large Nut211

A

C C

1

1

2

2

3

3

4

4

A A

B B

C C

D D

SHEET 1 OF 1

DRAWN

CHECKED

QA

MFG

APPROVED

One 10/3/2015

DWG NO

Stand Assy Weldment

TITLE

SIZE

CSCALE

REV

1

3

9

2

6

10

11

8

5

4

7

A43.75

90°

4.00

90° 90°

90° 90°

Lathe Stand Weldment Sub Assy

45.75

22.00.18Typ 4 Caps

.18Typ 4 Feet

.25 Typ 2 Legs

.25 Typ 2 ends

.18 Typ 2 Arms

2.00

4.00

23.25

4

5Drill and tapfor 3/8-16 FlatHead Screw,

2" Long, Qty 4


10

DETAIL AWelded PlateSCALE 1 : 1

Typ. 2 Places

A

1

1

2

2

3

3

4

4

A A

B B

C C

D D

SHEET 1 OF 1

DRAWN

CHECKED

QA

MFG

APPROVED

One 10/3/2015

DWG NO

Vert. Stand Leg

TITLE

SIZE

CSCALE

REV

.18 Ref.

2.00 Ref.

4.00 Ref.

P1.252X Thru

1.00 Typ 2

.625 Typ 2

P.61 Thru welded plate and Leg tube

2.00

1.25

.2-.5 grind smooth

.07 Weld Plate 2 Places

2.004X Typ

32.375

3.006.50

9.125

12.62

P.412X Thru

1.25 See Detail

Material: Steel Tube

Vertical Stand Leg

Note: 2 parts required mirror image

All Dimensions are in Inches

2x 0.438

2x 0.438 thru welded plate and leg

Clearance holes for ⅜-16 tpi locking


11

1

1

2

2

A A

B B

SHEET 1 OF 1

DRAWN

CHECKED

QA

MFG

APPROVED

One 10/3/2015

DWG NO

Leg cover plate

TITLE

SIZE

ASCALE

REV

4.00

2.00

.13 Ref.

Material: 1/8" Steel plate

Leg End caps

Note: 4 parts required.

All dimesions are in Inches


12

1

1

2

2

3

3

4

4

A A

B B

SHEET 1 OF 1

DRAWN

CHECKED

QA

MFG

APPROVED

One 10/3/2015

DWG NO

Lifting Arm

TITLE

SIZE

BSCALE

REV

10.00

1.63 Ref.

1.63 Ref.

Material: Steel Strut

.13 Ref.

Lifting Arms& Tool holder

Note: Perforated steel strut, 2 parts req.



13

1

1

2

2

A A

B B

SHEET 1 OF 1

DRAWN

CHECKED

QA

MFG

APPROVED

One 10/3/2015

DWG NO

Carriage stop angle

TITLE

SIZE

ASCALE

REV

.125 Ref.

1.38 Ref.

1.38Ref.

3.00

Note: 2 parts Required.Material: Steel Angle

Carriage Stop Angle



14

1

1

2

2

A A

B B

SHEET 1 OF 1

DRAWN

CHECKED

QA

MFG

APPROVED

One 10/3/2015

DWG NO

Carriage roller bracket

TITLE

SIZE

ASCALE

REV

.625

Clearance for 3/8 Bolt

.13 Ref.

2.81

1.38

Note: 2 Parts Required.

Material: Mild Steel

Carriage Roller Bracket

1.25

.688



15

1

1

2

2

A A

B B

SHEET 1 OF 1

DRAWN

CHECKED

QA

MFG

APPROVED

One 10/3/2015

DWG NO

Jack Plate

TITLE

SIZE

ASCALE

REV

2.00

.07 Ref.

.31 Typ 2

2.50

.31

1.38

P.222X Drill ThruChamfer 45`

Material: Steel Plate

Jack Plates

Note: 2 parts required.



16

1

1

2

2

A A

B B

SHEET 1 OF 1

DRAWN

CHECKED

QA

MFG

APPROVED

One 10/4/2015

DWG NO

Bushing Bronze

TITLE

SIZE

ASCALE

REV

1.00Ø ID

1.00

Material: Bronze

Bushing


BronzeBushing.com Part # EXEF162016

1 IN ID x 1.25 IN OD x 1 IN Length x 1.5

FLOD x 0.125 FLTH 841 Extra.

1.25 OD

.125

P1.50

Qty 4 Parts


Qty 8 parts

17

1

1

2

2

A A

B B

SHEET 1 OF 1

DRAWN

CHECKED

QA

MFG

APPROVED

One 10/4/2015

DWG NO

PVC Bushing

TITLE

SIZE

ASCALE

REV

1.50 Ref.1.25Ø

Material: PVC

PVC Bushing

1.625


Note: PVC ID to be clearance for Bronze Bushings

Qty 2 Parts


Qty 4 parts

18

1

1

2

2

A A

B B

SHEET 1 OF 1

DRAWN

CHECKED

QA

MFG

APPROVED

One 10/20/2015

DWG NO

Pipe to Jack connector

TITLE

SIZE

ASCALE

REV

2.50.25

1.25

P1.00

.25

Jack to Pipeconnector

Material: Steel

1.00

All dimensions in inches


Qty 1 part

19

1

1

2

2

A A

B B

SHEET 1 OF 1

DRAWN

CHECKED

QA

MFG

APPROVED

One 10/4/2015

DWG NO

Large Bolt

TITLE

SIZE

ASCALE

REV

4

1.00Ø

Material: Steel Grade 5

Large Bolt 1"-4.00 8TPI


Qty: 2 Parts


20

1

1

2

2

A A

B B

SHEET 1 OF 1

DRAWN

CHECKED

QA

MFG

APPROVED

One 10/4/2015

DWG NO

Large Nut

TITLE

SIZE

ASCALE

REV

P1.00

Material: Steel Grade 5

Large Nut 1" 8TPI & Washer


QTY: 2 of Each


21

PARTS LISTDESCRIPTIONPART NUMBERQTYITEM

Carriage Plate End21 Carriage Plate Gusset22 Carriage Angles23 Carriage lifting plate14 Carriage roller bracket15 Carriage stop bracket16 Carriage Large Plate27 Carriage Plate Gusset_MIRROR PART18 Carrage Plate Gusset_MIRROR PART19 Carriage plate end_MIRROR PART110 Carriage stop bracket_MIRROR PART111 Carriage roller bracket_MIRROR PART112

1

1

2

2

3

3

4

4

A A

B B

C C

D D

SHEET 1 OF 1

DRAWN

CHECKED

QA

MFG

APPROVED

One 10/3/2015

DWG NO

Carriage end weldment-1

TITLE

SIZE

CSCALE

REV

2

3

4

20.375

35.187

8.7504.375

.25

.25Typ Both Sides

Carriage WeldmentSub Assembly


43.437

2.187

2.682X Ref.

1.75

5.00 Ref.

2.0

1

56

7

3.125 3.125

30.125 Centered on Carriage.312 Typ.

2X 2.13

2X 2.87 Ref.


22

2.25 Typ.

1

1

2

2

3

3

4

4

A A

B B

C C

D D

SHEET 1 OF 1

DRAWN

CHECKED

QA

MFG

APPROVED

One 9/23/2015

DWG NO

Carriage end

TITLE

SIZE

CSCALE

REV

.00 4.00.00

4.00

.00

6.50

.00.00.00

8.25 Ref.

8.875

1.00 Ref.

4.375 Ref.

5.00 Ref.

2.50 Typ

.2

Material : .25 Mild steel Plate

Carriage End weldment

Note plates are reversed,on each end, (3 holes ref.)

Note: 2 Parts Requried, Mirror image

8.00

4.438

All dimensions in inches


23

1

1

2

2

3

3

4

4

A A

B B

C C

D D

SHEET 1 OF 1

DRAWN

CHECKED

QA

MFG

APPROVED

One 9/24/2015

DWG NO

Carriage plate end

TITLE

SIZE

CSCALE

REV

Material : .25 Mild steel

Carriage Plate End

.003.10 4.438 Typ 2

8.8751.96

.00

1.25

1.52

2.28

4.75

4.00

6.25

P 1.00 Nominal

.437 Typ 3

7.94.93

P7.00 Typ.


4.438

1.50 Ref.

All dimensions are in Inches

22.5` Typ.


24

1

1

2

2

3

3

4

4

A A

B B

C C

D D

SHEET 1 OF 1

DRAWN

CHECKED

QA

MFG

APPROVED

One 9/25/2015

DWG NO

Carriage Large Plate

TITLE

SIZE

CSCALE

REV

.00

8.00

.00 8.875

.25

Material : .25 Mild Steel

Carriage Large Plate




25

1

1

2

2

3

3

4

4

A A

B B

SHEET 1 OF 1

DRAWN

CHECKED

QA

MFG

APPROVED

One 10/3/2015

DWG NO

Carriage Angle

TITLE

SIZE

BSCALE

REV

43.25

1.25 Ref.

1.25 Ref..19 Ref.

Note: 2 parts Required.

Material: Steel Angle

Carriage Long AnglesAll dimensions in inches


26

1

1

2

2

3

3

4

4

A A

B B

SHEET 1 OF 1

DRAWN

CHECKED

QA

MFG

APPROVED

One 9/24/2015

DWG NO

Carriage Plate Gusset

TITLE

SIZE

BSCALE

REV

.00

4.00

.00 4.00

.25

Carriage Plate gussetMaterial : .25 Mild steel

Note: 4 parts Requried.



27

1

1

2

2

3

3

4

4

A A

B B

SHEET 1 OF 1

DRAWN

CHECKED

QA

MFG

APPROVED

One 10/3/2015

DWG NO

Carriage lifting plate

TITLE

SIZE

BSCALE

REV

7.50 7.50

1.00P

.25 Ref.

.25

Material: Steel Plate, Bar

Carriage Lifting Plate

2.00

3.75

3.75



28

1

1

2

2

3

3

4

4

A A

B B

C C

D D

SHEET 1 OF 1

DRAWN

CHECKED

QA

MFG

APPROVED

One 10/3/2015

DWG NO

I Beam

TITLE

SIZE

CSCALE

REV

Material : I Beam

Base I Beam

43.937

2.25

4.00

.07 Ref.


15.752X

22.882X P.25 Typ

.442X

1.812X



Changing Lathe from a Standing-to-Sitting PositionRefer to the photographs on Slides 1, 4 and 30.

Caution: It is critical that these instructions be followed exactly to maximize safety and ease of adjustment.

1. Make sure the rear lathe wheels are in the up-position and the stand is stable.2. Remove the tailstock and any headstock attachments from the lathe. Position the banjo all the way back on the lathe ways and near the

middle of the lathe.3. Make certain the wooden roller guides are still installed on the small brackets beneath the carriage’s front corners. If not, install them and

hand tighten the wing nuts.4. Make sure the 1.5” diameter x 8 ¼ ” long green pipe section is still installed between the scissor jack and the bottom of the carriage. If

not, slip it in place over the 1” diameter steel stubs and raise the jack by hand to barely make the pipe tight between the jack and carriage stubs. Rotate the pipe to make sure it is not binding and sits vertical over the center of the jack while adjusting its height.

5. Loosen the large grade-8 nuts on the 1” diameter pivot bolts.6. Loosen the ⅜-16 x 3” long locking bolts and nuts beneath the pivot bolts.7. Slightly adjust the scissor jack upward by hand until the 1” diameter pivot bolts and ⅜” diameter locking bolts rotate freely - usually a

fraction of a turn of the jack screw.8. Remove the pivot and locking bolts from both sides completely and set aside.9. Use an electric drill (or turn by hand) to slowly rotate the jack screw counter clockwise approximately 20 rotations until the pivot holes in

the carriage vertical end-brackets align with the lower set of bronze bushings in the vertical legs. Keep the carriage level by-hand if necessary while lowering it so it does not “rack”, or adjust the position of the banjo slightly left or right on the lathe ways.

10.Install the 1” diameter pivot bolts through the aligned pivot holes, from the outside toward the inside. Install the large washers and hand-tighten the nuts.

11.Continue to lower the scissor jack all the way until the green pipe can be removed from between the jack and carriage steel stubs. (Lift the pipe all the way up on the carriage’s stub and rotate the lathe/carriage assembly slightly towards you so the pipe bottom clears the jack’s stub. Store the pipe on the magnets inside the I-beam.)

12.Remove the wooden roller guides from the brackets on the bottom corners of the carriage and store inside the pipe section until needed again to raise the carriage.

13.Rotate the lathe/carriage forward so the 7/16” dia. holes in the 45 degree position of the carriage end brackets align with the center holes in the vertical legs.

14.Insert the ⅜” dia., 3” long locking bolts in those 45 degree position holes from the outside of the legs. Install the washers, lock washers and nuts in the proper order and tighten securely with a pair of 9/16” wrenches.

15.Tighten the 1” pivot bolt nuts securely using the 1.5” box wrench on the bolt head and your other hand on the nut and extended bolt threads. This is sufficient to lock the pivot bolts without deforming any other components.


45 degreelocking bolt

position

Sitting Pivot Bolt Position

0 degreelocking bolt

position

Standing Pivot Bolt Position

Storage for morse tapered tooling

Lift plate


Changing Lathe from a Sitting- to-Standing PositionRefer to the photographs on Slides 1, 4 and 30.

Caution: It is critical that these instructions be followed exactly to maximize safety and ease of adjustment.

1. Make sure the lathe wheels are in the up position and the stand is stable.2. Remove the tailstock and any headstock attachments from the lathe. Position the banjo all the way back on the lathe ways near

the middle of the lathe.3. Loosen the 1” pivot bolt nuts using the 1.5” box wrench on the bolt head and your other hand on the nut and extended bolt

threads. Do not remove the bolt!4. Remove the ⅜” dia., 3” long locking bolts from the 45 degree position holes of the carriage brackets and leg center holes, using

a pair of 9/16” wrenches. Set bolts aside until step 11.5. Return the lathe/carriage assembly to the 0 degree position while inserting the 1.5” diameter x 8 ¼” long green pipe between the

1” steel stubs of the jack and carriage lift plate. Adjust the jack by hand if necessary to get clearance. Rotate the pipe to make sure it is not binding and sits vertical over the center of the jack while adjusting its height.

6. Install the wooden roller guides’ ⅜” bolt ends through the small brackets on the bottom front corners of the carriage, so that the wood rollers align with the 2” width of the vertical legs. Tighten the wing nuts securely.

7. Raise the scissor jack slightly so the pipe section just begins to feel the load of the lathe and carriage.8. Remove the 1” diameter pivot bolts completely. Make slight adjustments of the jack height by hand if necessary so the pivot bolts

slip out easily.9. Carefully raise the lathe/carriage assembly by cranking the jack screw clockwise by-hand approximately 20 rotations; or better

use an electric drill at low speed while maintaining the carriage level to prevent racking as it raises. Align the pivot bolt holes in the carriage ends with the top set of brass bushings. Remove the drill.

10. Insert the 1” diameter pivot bolts, from the outside toward the inside, and loosely tighten the nuts on the washers. 11. Lower the jack about ¼” to release any upward force on the carriage.12. Install the ⅜” dia., 3” long locking bolts through the top, centered, 7/16” diameter leg holes into the 0-degree position holes of the

carriage ends. Tighten the locking bolts securely using a pair of 9/16” wrenches. 13. Tighten the 1” pivot bolt nuts securely using the 1.5” box wrench on the bolt head and your other hand on the nut and extended

bolt threads. This is sufficient to lock the pivot bolts without deforming any other components.

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y1

Floora) Endview, 1st

balancec) Sideview, 3rd balance

z

c.g. position along z-axis

y1y2c.g. position

in xy plane

b) Endview, 2nd balance

zx


Finding the Center-of-Gravity of the Lathe and Carriage

If you use a different midi-lathe than the Delta 46-460, some of the exact carriage dimensions may need to be modified to maintain good balance of the lathe/carriage assembly on the stand, due to a change in location of the center-of-gravity of the lathe and carriage assembly. As discussed in connection with some of the parts drawings, a critical part of this design is that the lathe and carriage assembly is balanced with respect to its rotation about the pivot bolt axes and with respect to the scissor jack lift axis. To achieve this balance it is only necessary to position the center-of-gravity point of the lathe/carriage assembly at the intersection point of the carriage pivot bolts’ axis and the vertical lift axis provided by the 8 ¼” long pipe.

Measuring and/or calculating the height of the center-of-gravity of the lathe/carriage assembly is necessary to determine the height of the pivot bolt holes in the carriage end-plates above the bottom plates of the carriage to which the lathe is bolted. Measuring the horizontal position of the center-of-gravity of the lathe/carriage assembly is necessary to determine where the carriage lifting plate is located and where the scissor jack is located on the I-beam. Since the pivot axis and the lift axis are perpendicular to one another, the position of the center-of-gravity along them can be determined independently for each direction.

Since the carriage pivot holes and lift plate positions cannot be determined until the lathe/carriage center-of-gravity (c.g.) is determined, which can’t be done until the location of the lathe and lift plates on the carriage are determined, it may appear as though there is a catch 22. But fortunately, since the carriage is symmetric about its horizontal and vertical axes (ignoring the slight offset of the lathe mounting holes) we can assume that the carriage’s center-of-gravity is coincident with its center-of-symmetry. We can easily measure the location of the lathe’s center-of-gravity with respect to a reference point on it (e.g. the center of one of its mounting bolt holes in the bottom plane of the lathe), and then using some simple linear equations (physics 101) to calculate where the c.g. would be for the combined assembly of the lathe plus carriage together. It is important to have the tail stock and banjo fixed to the ways and located where they will be when changing the stand from sitting to standing.

The figures above illustrate how to find the c.g. of an object like a lathe. Tape a sheet of paper to one end and balance the bottom of the lathe on the peak of a long steel angle aligned parallel to its length, as in a). Use a square to draw a vertical line perpendicular to the floor through the peak of the steel angle to define a first axis y1 that goes through the c.g. Next steady the lathe by hand so that it is balanced on the floor on one of its edges, as in b). Use a square to draw a second line on the paper that goes through the 2nd balance point (corner) of the lathe to define a second axis, y2, that goes through the c.g. Where y1and y2 intersect defines the c.g. of the lathe in the xy plane. In Figure b) the z-axis points out perpendicular to the xy plane. Next, turn the steel angle perpendicular to the long axis of the lathe and move lathe parallel to its long axis, z, until it is balanced again on the ridge of the steel angle, as shown in figure c). This defines the position of the c.g. along the z axis.

33

So the distance of the carriage’s c.g. from the left most edge of the lathe’s cast iron base is just half the length of the lathe, or 31 ⅛”. In Figure d) the quantity D is the unknown and needs to be determined. The balance equation is:

( D-12.25” ) times 97 lbs = (15.5” - D ) times 30 lbs.

Solving this for the quantity D gives D = 13.0 inches. This then specifies where the jack’s lift axis will have to be located with respect to the reference plane end of the lathe.

A similar calculation can be done to determine the vertical height of the pivot axis above the bottom of the carriage to locate where the 1” bolt holes are to be drilled in the carriage end brackets. This is a bit more complicated since the distance of the c.g. of the carriage in the y-direction above the carriage base is not so obvious due to the asymmetry in the horizontal plane (gussets, non-square end plates, steel angles, etc.). But the principle is the same, and can be used to find that the c.g. of the lathe/carriage assembly is 4.75 inches above the bottom of the lathe where it sits on the carriage. A different lathe of course might produce a different result.

Figure d). Finding the c.g. position along the z-direction of the combined lathe and carriage assembly from the c.g.’s of the lathe and carriage measured separately.

Carriage c.g.Lathe c.g.Assembly

c.g.

Reference Plane - left

edge of lathe cast iron base.

97 lbs 30 lbs

D

12.25”

15.5”


Finding the Center-of-Gravity of the Lathe and Carriage - continued

Chose some point on the lathe as an origin, e.g. the center of one of its corner mounting holes, and measure the distance of the c.g. of the lathe from that choice of origin along each of the symmetry x,y1,z axes. You now have the coordinates, (x,y1,z) for the c.g. of the lathe. For the Delta 46-460 lathe that we mounted on this stand, the c.g. I found by this method was shifted 0.5 inches towards the rear of the lathe along the x-direction, due to the asymmetric location of the motor. Similarly the motor is mounted beneath the head stock which shifted the c.g. along the z-axis closer to the headstock, or 12.25 inches from the left-most edge of the lathe’s cast iron base. Finally the c.g. was found to be 6.375 inches above the bottom of the cast iron base in the y1 direction. For these values, the tailstock was removed from the lathe bed and the banjo was located next to the head stock.

The next step is to use the above information to find the location of the c.g. of the combined assembly of the lathe and carriage. For this we need the original good assumption that the c.g. of the carriage alone is located at its geometric center in all three spatial directions x,y,z, since it is symmetric about the two vertical planes, and we need the weights of the lathe and the carriage. The Delta 46-460 weighs 97 lbs, and the carriage weighs 30 lbs. For each axis direction there is a simple algebraic equation based on the principle of balanced torques, that can be solved to find where the c.g. coordinates of the lathe/carriage is located in terms of these weights and c.g. coordinates of the lathe and carriage measured separately. This is discussed next for the case of balance in the z-direction, along the long axis of the lathe/carriage.

The figure below illustrates this for finding the c.g. of the lathe/carriage assembly along the z-direction, that is along its long axis. First it should be obvious that the c.g. of the combined assembly will lie between the c.g. of the lathe alone and the c.g. of the carriage alone. The distance of each component’s c.g. from the combined c.g. is called a moment-arm. The physics principle is that if the lathe/carriage assembly were to be balanced on a steel angle as in figure c) on the previous slide, then the weighted moments (weights times the moment arm distances, or torques) are equal, as shown in figure d) below. Because the combined assembly is by definition balanced on its c.g., the torques on either side of the balance point cancel one another. In this figure, the reference plane for the distances shown is the left most edge of the lathe’s cast iron base bottom. I chose to mount the lathe centered on the carriage’s center along the z-axis, that is the long axis of the assembly, just so it looks centered, with equal distance between the end of the lathe and the carriage end brackets.

34

Fabrication Process, Assembly and Operational Comments

I used a Millermatic 211 MIG unit for all the welding. Cutting the various steel tubes, I-beam, angles, rods and other smaller items to the precision lengths with exactly square ends were easily done with an Evolution EVO-380 metal chop saw with a 15 inch diameter carbide blade. More difficult were the large, ¼ inch thick steel plates used to construct the carriage, which were fabricated from longer pieces of cold-rolled plate stock using a 10” radial arm saw and standard metal cutting blades - the most difficult part of the whole process.

It is important to use standard, good methods for maintaining alignment of the subassembly parts during welding. Lay the parts out on a large, truly flat surface so that precise right angles can be maintained during the welding. Begin with the stand’s leg parts, making sure the vertical and horizontal members are held exactly perpendicular using diagonal measurements rather than a square, which I found not to be sufficiently accurate. When the I-beam is welded between the two T-shaped leg subassemblies, make certain the vertical members of the leg subassemblies are maintained exactly parallel to one another so that the spacing at the top of the legs where the carriage sits is the same as where the I-beam is located. If possible, tack-weld the I-beam in place while the carriage is in the stand-up configuration on the stand, and the 1 inch diameter pivot bolts slip easily in and out of the bronze bushings without binding. Then you know the vertical legs are precisely oriented while the horizontal feet are resting equally on the flat surface or floor.

As discussed on slide 7 in connection with the I-beam, if the stand is on an uneven floor, and the Pivot and locking bolts are loosened, the weight of the stand and lathe will produce a torque that will rotate the frame very slightly about the I-beam so that all four feet to remain on the floor. This may cause the carriage pivot holes to slightly misalign 20 or 30 thousands of an inch with the bronze bushings in the vertical leg members, since one vertical leg will twist in one direction and the other vertical leg in the opposite direction, binding the pivot or locking bolts so you cannot easily remove them. If this happens, adjust the feet screws of the stand so that the pivot bolts and locking bolts slip easily by hand in and out of their respective holes. Once the alignment is good and the locking and pivot holes move easily in their respective holes, tighten them down to lock the carriage firmly in place. It does not take a lot of torque on the wrench for the 1 inch bolts to lock securely, so don’t overdo it and deform the end bracket of the carriage or the tubular steel of the vertical leg members.

You may wonder why class 5 or 8 machine bolt strength is specified for the 1 inch diameter pivot bolts that the carriage rotates about. It is simply that for bolts that large, that is what is commonly available at home/farm supply stores for a few dollars apiece. In this case, the bolts’ large diameters are serving to give more bearing surface with the bronze bushings for smoother rotation rather than strength. But it is also true that the threads will never likely get stripped.

Although not shown, you may also want to weld-up a y-shaped tool rest with an included 45O angle. I used ⅝” diameter cold rolled rod. Slice the top end of the old that fits into the banjo at 45O and lay the horizontal piece on it, offset slightly, and tack weld it. Then fill in the weld fillet. When in the sitting position, this allows the tool rest bar to be parallel to the floor rather than tilted, which is useful for hollowing out bowls or in general work from the tail stock end.

We have tried to make sure that all the dimensions and design elements specified in these drawings and slides are free from errors and incomplete dimensions. But there is always the chance some slip-ups remain and probably even more likely that something is not explained sufficiently as to how parts are to be assembled. If you have questions about the stand’s design or fabrication steps, you can contact myself at [email protected]. If you have questions about the interpretation of the CAD drawings, symbols or would like to discuss employing Tom Kindom to make such drawings for a project of your own, you can contact Tom at [email protected].

We bear no responsibility for any injuries that may occur due to modification of the design or failure to follow the safety instructions for operation of the lathe stand or while changing it from the standing-to-sitting configuration and vice versa.


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