Has anyone disassembled or rebuilt a Mk5 speed reducer ?

[john_520]

Nothing wrong with my reducer at this point, I'm just wondering if anyone has disassembled one for inspection or repair. Can anyone tell me if the 4 small black inspection covers on the back housing can be removed somehow ?

At this point I'm mainly curious about whether the output shaft can withstand much in terms of milling side forces, based on how it's engineered.
Is it almost entirely an accessory driving device when compared with the headstock quill for example ? It seems to me if the reducer output shaft is robust enough to mill a larger diameter wood bowl in a lathe operation, milling very small aluminum, copper or brass stock shouldn't be much more damaging (despite being "not recommended").
I wouldn't mill soft metals often enough to justify buying a metal lathe, not to mention the extra room or shipping involved. Speed reducers appear to be fairly simple and user serviceable, if you can order parts and get specs for correct belt tensions.

If it could withstand some degree of milling forces at the output shaft, I was contemplating fabricating a four point way tube mounted base for the reducer housing instead of the current 2 point plus collar mount,
so less stress would be transferred to the reducer collar to headstock coupling (plastic shaft coupler inside).
$82 in reducer parts required for a rebuild seems acceptable if infrequent, and if it can be performed by the user. SS charges $80 labor for a rebuild + shipping I was told.

Hoping to hear your opinions + personal experiences with these units.

Thanks !

[charlese]

Hi, John! The little black plugs pop out with only fingernail pressure. The first time doing this I used a small flat screwdriver.

Both drives in the speed reducer a turned with poly-V-belts. They need to b fairly tight. There are adjustments on both sides.

Why use the speed reducer for turning soft metals? I used the regular lathe function of the Mark V to turn small brass hammers.

[john_520]

Thanks charlese, I didn't want to remove plugs without being sure 1st.
I'll have a peek inside the housing for a structural assessment.

I'd love to hear your impressions on brass turning jobs.
I've cut aluminum and brass on the band saw but that's about it so far. No milling work yet.

Why use the speed reducer for turning soft metals? I used the regular lathe function of the Mark V to turn small brass hammers.

1- I have a 6" four jaw metal lathe chuck l would mostly be using. I'll probably tap the chuck 5/8 collar for a 2nd set screw.
2- I thought reducer turning speeds would be more in line with most recommended metal turning speeds.
3- Probably about 7 to 8 times more turning torque off the reducer shaft after accounting for parasitic belt/bushing friction losses.
4- If the reducer output shaft housing doesn't die a premature death milling metals, rebuilds would hopefully be simpler and less costly than a quill rebuild I'm guessing. Never rebuilt either. Just a guess based on SS parts prices quoted at this early juncture.

Experience has taught me that my loftier ideas are often impractical however ... ...
and Shopsmith disclaimers suggest that's the case here.

[charlese]

Unfortunately, I bought hard brass and should have gotten a bar a little softer. All I could manage is making small rings (decorative) around the head and smooth and round the pein side of the hammer heads. Lathe tool was a skew. Incidentally - sawing pieces off of the bar was made easy with the lathe. Only had to move the hack saw slowly.

[ATTACH]20708[/ATTACH]

[terrydowning]

I too have turned brass (3/8" round stock) and aluminum (T-6061 5/8" round stock) on the lathe at slow speed. Go slow, use very sharp tools. Do keep in mind that you are using a wood lathe and not a metal lathe. If you need precision turning (thousandths of an inch) you will be better off with a metal lathe with closer tolerances, slower speed, and a cross slide with a fixed cutting tool.