Watchmaker's Lathe Overhaul (WIP)

I re-mounted the K&D motor so that it is direct drive to the pulleys of the lathe. This orientation should allow the periodic oiling to weep into the wick and keep the bushings lubricated.

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The highest and lowest speeds from these two sets of pulleys didn't seem to faze the five different samples of steel shafts that I have. either the speed needs to be higher/lower, the three gravers I have aren't cutting very well, my technique is not adequate, or ?????? I took the foot pedal "speed controller" off the sewing machine motor and adapted it to the K&D motor, but slower speeds didn't help appreciably.

Hmmmm. Think I'll go back and try turning a piece of 3mm brass. . .

. . . The brass was actually 1/8", or 3.18mm. I had to chuck it in my drill motor and file/sand it down to 3.06mm before it would fit into my #30 collet without being forced. It turns pretty good, but not like the YouTube videos I have seen. I suspect that technique is a significant part of the problem.
 
what are you using for a cutting tool? If the profile isn't right, it won't cut. Same if the point isn't on centerline of the material.

also, I thought that thing had an actual cross slide and a small lantern style tool post? Whats on there looks like a rest for a wood lathe.
 
I am using 2X2mm and 4X4mm HSS gravers cut on a 45°, forming a diamond. I finished
the face
on two stones and polished it on hard leather. I'm using the tool rest on the advice of a horologist.
The cross slide has no vertical Vernier adjustment.

The El Cheapo digital tach arrived today but I haven't taken the time to set it up and try it out.
 
slides won't have vertical scales, they only move horizontally. Vertical centering is basically by eye. I tweak it till it looks centered on the end of the stock and confirm by facing it. If it doesn't leave a pip, the height is right.

mostly I don't like the idea of having to control the tool position by hand because its harder to be consistent.
 
I'm trying to find a speed that will work with one of the batches of steel that I have. Next effort will be to develop a technique.

The cross sled definitely wins for repeatability.

I'll bring what I have to the Gathering - - -
 
cool project.
have you considered a DC motor and a controller? You can dial in intimate speeds to a fine level.
 
Leather will round the edges. Hollow grind then finish on a hard stone using the proud edges to guide the stone. It only takes a stroke or two to destroy a lot of previous work, so don't let the edges lift. No strop, no sandpaper, no lapping film just a hard stone.
 
Mike: I thought about a DC motor but I don't have a good DC supply. I have a 30v B&K 1660A lab supply with a problem that I have not been able to resolve.

Conrad: My notes are better than my memory!
I went back to my notes from early April. I bought the gravers and a “hard” Arkansas stone in late March. The gravers were hollow ground on a fine wheel (10” I think) at the shop of the woodworkers guild. I refined that with a crystolon combo stone, then a Queer Creek bench stone, and finished with the Arkansas stone. No mention in notes of using the piece of leather that I have used to polish a knife blade or two.

Edit: I made a 45° triangle of maple as a guide to keep the gravers aligned.

I purchased an "economical" digital photo tach but my findings have been inconsistent so far. I need some OJT on this one because RTFM isn't working out so well. I get average readings of ~2K to ~3K rpm using different pulleys, but the "max" has been 27K to 33K, all with a motor rated at 3,500 rpm.
 
no way that thing is running 30K. The bearings would never suffer that. I've honestly never tried my cheapie over about 1500 rpm but I do know it gets funny if you're running it against a reflective surface. Try maybe wrapping whatever surface you're reading off in black electrical tape and using one strip of the reflective tape to see if that makes it read normal.
 
The end of the Bakelite pulley block away from the collet has a series of registration holes that have a specific utility, that I don't remember right now. I suspect that my hand is not stable enough to keep the laser from wavering and sometimes getting reflections from these holes, thus giving a much higher reading.

I secured the digital tach gun in a wood vise and positioned the lathe such that the laser only strikes the outer ring of the pulley, outboard of the circle of holes, and always strikes where I applied the reflective tape. Now I consistently see numbers from ~1600rpm up to ~2900rpm, using the foot pedal controller and different combos of pulleys. Next step is to find the spread sheet that I set up to convert from rpm to SFM (Surface Feet per Minute) that the cutting tool will see at the rim of the 3mm shaft. One of the lathe books I found has a table listing the preferred range of SFM for several types of metal.

This is the tach that I got:

TL900.jpg
 
Mine is more box shaped, the sensor is on the end of it. The "gun" style would probably be easier to use. 1600-2900 sounds a whole lot more reasonable though.

If you haven't read it yet, a copy of South Bend's "How To Run A Lathe" would be worth a perusal while in the throne room.
 
The TL900 reads min, max & avg. The seemingly erroneous "max" readings of ~30K will skew the "avg" readings and the instantaneous handheld readings fly by so quickly that I cannot read them. I would only recommend this tach to someone with a very steady hands, or a good vise.

I'm thinking that the best way to handle the speed issue is to take it off the foot controller and use the vise setup to record the speed for each combination of pulleys, and use that as a reference. Perhaps somewhere down the line I can find a VFD that works with low Hp motors.

Yes, I have South Bend's on a CD. Also have Donald de Carle's "The Watchmaker's and Model Engineer's Lathe: A user's Manual", plus a number of articles I have sniped off the Internet. Converting some of this theory into practice is what I am having some difficulty with. You have to develop some experience before you can expect to do this consistently.

We are getting ready to have the siding replaced on the house. There are many things that need to be done in preparation, and my wife keeps finding more things that she wants to have done. I am not as efficient at time management as I use to be, so the lathe doesn't get powered on very often. 'Nice to have a "log book" here on AK so I don't lose track of an important suggestion.
 
I rigged the tach in a vise and positioned the lathe so that the laser hits the outer band of the pulleys, where there are no index holes. Then placed a piece of the reflective tape on the pulley. I have the K&D motor on the foot pedal controller so I ran it "full throttle". After it stabilized I ran the tach for ~5 seconds on each of the 12 combinations of pulleys. The measured speeds ranged from 1550rpm up to 2695rpm, giving me a range of 58.2 to 101.2 SF/M.

The readings were not consistent so I may need to repeat that with the tach a little closer to the pulley. 1st trial was about 80cm.

According to the chart of "machine speeds" that range of SF/M should cover most of the sample of steel 3mm rods that I have accumulated. But I was not able to get a "good turning" on any of the rods over that range, leading to the conclusion that my technique needs significant improvement, my grabbers are not sharpened correctly, or who knows what else I am not doing right.

I will keep trying - - -
 
A lot of it has to do with the grid of the cutting tool, and position relative to centerline. I've got no experience doing it with a graver, but for a standard bit in a tool holder, it wants to be on center with relief ground on the bit so it only contacts at the front corner. Without relief the bit just rubs and it does nothing but make heat. Off center and it mostly does the same thing. I would presume a graver would work in a similar fashion.
 
BillWojo and Gadget73 showed me how to use the cross sled on the lathe (Thanks!!). It took me a while to get the sled squared up to the bed and I have finally made a couple of turnings. The basic shape is there but I need a lot of improvement in technique. The surface of the turned area needs to be smoother, and better definition in the corner.
The cross sled has noticeable backlash in both axis so I need to do some more reading to see if I can make some adjustments to improve that.
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