Ralph Patterson Speed Reducer 1

8/12/2019 Ralph Patterson Speed Reducer 1

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20/3120 of 30.

Hmmm; Not exactly a sharp photo, but it is the only one available to illustrate the installation

of the adjuster plate, pc 6 in the drawings. Two fasteners pass through the lathe bed slots to

mount the plate. Note that there is no projection of the bolts through the plate, which would

interfere with the mounting of the Jackshaft assembly. The slotted mounting holes allow

adjustment of the plate/jackshaft in the vertical, as well as some flexibility to adjust rotation to

bring the driving and dreven pulleys into the same plane. The lower pair of threaded holes will

accept the fasteners that mount the Jackshaft assembly. These fasteners, also must not belonger than the thickness of the adapter plate so that the Jackshaft may be mounted securely.

This photo, as were all but the last one, were made during a partial teardown of the lathe after a

long period of usage. Judging from the amount of chips colledcted in the bottom of the bed, the

cover does not provide complete protection of the works from flyaway chips. Some more

development work is in order, I guess. Some of the mess might have entered through the round

hole that is intended to provide access to the motor brush holder on a standard configuration

lathe. On the far right is the stud and securing nut of the post that clamps the Banjo to the lathe

bed. This part has been altered to make adjustment of the Change-Gear train easier and simpler

More about this mod on a later page.


21/3121 of 30.

This page shows the lathe-side of the Jackshaft assembly. The slotted holes (a little crooked)

are positioned to allow a long, ball-point, T-handle Hex tool to access the Socket Head Cap

Screws that secure the part to the Adjuster Plate. The length of the slots is sufficient to bring

the pair of pulleys into line. All of the flat head screws on this surface must be at or below

flush with the angle so that the part is clamped tightly to the Adjuster Plate. The two

additional fasteners on the top side are not critical, could even be another style of screw head.

The drawing on sheet 17 shows the use of Hes Head CAp Screws, but there was no room to

pass a socket under the shaft of the assembly, so SHCS fasteners were substituted. Yourexperience may be different.

In this view, the assembly is fitted with the costom-size dreven pulley, with 41 teeth. The

custom pulley can be as large as 43 teeth and still fit comfortably under the stiffner rib on the

lathe bed, as can be seen on page 29. Also, the pulley is made of clear Polycarbonate plastic,

3/8" thick. A standard pulley is 10mm thick, but, a new belt is only .355" wide, so the thinner

pulley will still have plenty of width on the driving surface, and make full contact with the belt.


22/3122 of 30.

The motor side of the Jackshaft assembly. The spacer used between the bearing on the right

side and the pulley, provides a clearance for the pulley away from the bearing boss of .025

inches. This has proven to be adequate in operation. The two pulleys share a common 3mm

square key, driven by a slot in the surface of the shaft, as shown in the assembly illustration, on

pg 17. However, the illustration of the assembly shows a standard 31 tooth pulley (with a

10mm bore) and the step key to drive the two pulleys of different bore configuration. There is

no difference of capability between the two drive setups that can be observed. The custom

pulley offers a choice of drive ratios for the final speed reduction.

The two small threaded holes on the top of the assembly will accept the fasteners that secure the

sheet metal guard to the Jackshaft assembly. The guard ensures that none of the wiring parts

can become entangled or rub on the rotating shaft. It would be sad if a wire was rubbed all the

way through the insulation and then create a short circuit in the motor connections.


23/3123 of 30.

Underside of the Jackshaft assembly. The fasteners do not have to be flush, and could be

substituted with Button Head screws. The cover, mentioned on the previous page, was formed

of a piece of .020" thick Aluminum flashing. The bends could have been a little sharper.

Included in the view is the plastic cable clamp that helps keep the cables under control and

away from the moving parts. The screws are #8-32, but could have been M4.0 just as well.

Ths part on the right is the nutplate that fits inside the Unistrut used for a lathe foot. The plate

provides a purchase for the two screws that secure the motor support angle to the foot, and can

provide adjustment of the motor position for belt tension adjustment.


24/3124 of 30.

Here be the motor support Aluminum angle. Once the angle is mounted to the lathe foot, the

motor is set on the bottom leg of the angle, and the motor-mount studs pass through the middle

pair of holes in the back of the angle. It was soon found that belt adjustment was too

complicated if one tried to estimate the correct position of the angle, then install the motor and

belt. Therefore, the two additional screw holes were included, tapped for adjusting screws that

will bear against the motor body, were included in the part.

After the angle is secured and the motor is mounted with the two studs, final position can be

adjusted by manipulation of the screws against the motor, both for center-to-center distance, but

also for angular position with respect to the belt. These adjustments regulate tracking of the belt

on the center of the pulley.

If you look closely at the setscrew on the right side, there is a crescent shape adjacent to the

screw. This is the tattletale of re-locating the screw so that the locknuts on the opposite side do

not interfere during adjustments. A piece of Aluminum rod was turned to 6mm, then threaded

to be a tight fit with the threaded hole. It was turned into the hole with a coat of red Loctite.

After the cure period, the excess was filed flat, and a new hole drilled and tapped.


25/3125 of 30.

Backside of the motor support angle. Now you can see the clearance problem that existed

between adjacent holes when there were nuts and washers on the motor studs. The adjustment

of the outer pair of screws could be easier if they were thumbscrews with knurled knobs instead

of the SHCS shape. Maybe just make some knurled knobs to press on to the screws that are

shown. Alternatively, some press-on knobs for the Socket Head Cap Screws from Reid Tool

Supply would work nicely.

This piece of Aluminum angle came from a scrap bin, and had a coat of light gray paint on most

of the length. When the burrs were filed away from the new holes, some marring of the paint

was done. Installation of the bolt and jam nut has hidden the evidence of the old hole in the

undesired location, except for the file marks.


26/3126 of 30.

Time for a trial fitment of the Jackshaft in the motor bay of the lathe. The Adjuster Plate has

been bolted through the slots in the lathe casting, then the Jackshaft assembly mounted to the

plate. the belt to the Headstock has been aligned visually, but must be refined for tracking

when the setup is operated under motor power. The large pulley shown is the 41 tooth

custom part, and the second belt was purchased from Little Machine Shop.

In the lower foreground, the Unistrut lathe foot is shown, with the two slotted holes for the

motor mounting fasteners. The Nutplate will slip inside the foot, and the fasteners through

the motor-mount angle will thread into the plate. About .50 inches of adjustment isavailable. When the pulley was changed from 31 tooth to 41 tooth, some extension of the

mounting slots was required. Being too lazy to up-end the lathe to remove the foot, the work

on the slots was done with a metal-cutting burr in a Dremel Tool, a little crudely. Through

the slot on the left, you can see the spring that is part of the Unistrut nut that is used to mount

the rubber foot to the underside of the foot. The spring is sort of a nuisance, but, it holds the

nutplate firmly in position to allow installation of the motor support angle fasteners.

Note the flat bar on the underside of the Foot. It was found at the Home Depot store and used

to provide support to the rubber foot as the fastener was tighened. This is changed in the

drawing pages, the large fender washers in the drawings were found at another store after this

assembly was constructed. If I need some more of the flat bar, I know where it is stored...


27/3127 of 30.

The motor support plate is loosely in position, ready to mount the motor. After the motor is

secured with the flat washer, lock washer, and nut components seen on the top of the bed,

the whole of the assembly can be located approximately for belt alignment and length. The

spring force on the underside of the nutplate is helpful to keep things in position while the

motor is again removed to tighten the two flat head screws. A couple of iterations might be

required to get it all correct. Final belt adjustment is done with two outboard screws that

protrude through the back of the angle. Loosen the motor stud nuts, then push the motor

away from the angle with the adjuster until the belt conditions are satisfied, then lock allfasteners down securely. It was fairly easy, once worked out and practiced.

Notice the crimp connectors used to extend the motor leads that connect with the terminal

strip on the controller board, located on the opposite side of the lathe bed. The loose leads

are an invitation to disaster, I have to admit. They should be sheathed in shrink tube that

has been shrunk around the jacket of the motor conductors. If not that, then replace the

entire motor pigtail with one of sufficient length.

To be honest, these photos are not of the original assembly, but of things laid out on the

occasion of a teardown to investigate the modification of something else, so the growing

pains have already been experienced, and the procedure fairly well established.


28/3128 of 30.

Here is an end-view of the lathe, ready to mount the drive train components. The cover

over the HS countershaft pulley is still in position.

The Adjuster plate is installed on the interior of the Motor Bay of the lathe bed, ready to

accept the Jackshaft with it's two fasteners. The motor is staged on the top of the bed,and

the motor cover is standing on-end with the wiring attached. Note the salvaged cable

clamp that is pop-rivited to the inside of the motor cover. The little un-painted tab on the

motor cover was an afterthought to plug the gap between the cover and lathe bed, for

control of chip entry to the inner workings.

Two bolts will remove that, soon.

Other features to be seen in this view are the "Reverse Lockout toggle switch on the side of

the controller cover (plan found at http://www.mini-lathe.com), and the customized Banjo

clamping stud on the end of the lathe bed. When this lathe was new, the standard stud was

badly installed on the lathe; the hole was not the correct distance from the Leadscrew, and it

was drilled at an angle. The stud would pass through the drilled-out hole, OK, but is still not

the correct distance. A new stud was made with the shank eccentric to the centerline so that

the position can be adjusted by rotating the stud while tightening. The outer 6mm stud is

gone, it is replaced by a M6 threaded hole. The Banjo is now clamped by an exterior screw.


29/3129 of 30.

All of the drive train components are re-installed, and the belt adjustments are completed.

The remaining tasks are to mount the various covers and the controller box, and finally, the

change-gear components.

On the lower right side of the view, you can see the lathe chuck key and various sizes of

frequently used Allan (hex) wrenches nested in their respective holes that have been drilled

through the Foot of the lathe. It is very handy, and the little ones do not get lost in swarf as

was the case before a home was created for them.

On the end of the spindle, notice that the outboard locknut has been replaced with an

extension thingie, one of the first projects done on the lathe for the lathe. Drawings for

that project were posted in "Photos" on the 7x10minilathe site, and are also available in PDF

format in the collection of drawings at http://www.savefile.com/projects/808585083.

About 20 designs in PDF are stashed there for as long as anyone wants to download them.

The bad news is that if there are no more downloads in 60 days, the files are removed from

the archive. So far, I be too cheap to pay the fee to guarantee permanent residence on their

server machine.


30/3130 of 30.

The final view of the Jackshaft Speed Reducer project, ready for the mounting of the cover.

This view was made while the original 31 tooth driven pulley is installed on the jackshaft.

The motor-mount nutplate is visible peeking out from beneath the motor and it's mounting

angle. Once properly installed and hidden by the motor cover, this is a nice alteration to the

lathe. Nothing on the lathe was actually modified, except for the theft of the cable clamp

from the original motor cover. If you ever want to sell the lathe and keep the Jackshaft kit for

installation on another machine, all you need repair is the clamp, maybe make use of

commercial moulded plastic cord locking things with a built-in strain relief part.

Also, in this view, you can see the screw that clamps the Banjo with change-gears to the

new stud using a flat head hex drive screw and a thick washer that is countersunk to accept

the FH screw. Some care is needed to keep the screw/washer thickness small to avoid

dragging on the larger gears that may be used in the train. These gears are setup for

cutting 20tpi threads. The small white gear on the B/C shaft is my 21T gear being used as

a spacer for the 65T idler that links gears A and D, on the leadscrew.

On the end of the spindle is a better view of the spindle extension described above. It's

purpose is to direct chips outside of the gear cover so that none are trapped in the gear

teeth. That does a bad job on the gears and is one of the causes of poor finish on turnings.

Job is complete!


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Ralph Patterson Speed Reducer 1

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