Another 10" Logan Project + A Question

That chip guard looks real nice. I'm planning to build out my "light bar" a little bit (toward the spindle an inch or so) to have room to extend a guard inward and clear the motor. Really good idea to use a rubber cushion.

Nice clean finish on the VFD mount also.
 
Thanks Tom. I have to confess I'm not responsible for the finish. I had a batch of parts that needed painting (including non-lathe stuff), so it all went
to the powder painter. I'm also lucky: there's a sheet metal shop where I work, and they let me use the brake any time I want.

What's your light bar?
 
Nogoingback said:
Bent up and painted a simple backsplash from sheet steel to keep some of the oil and chips off the floor. It's held with screws to the rim of the chip pan at the bottom, and
rubber mounted at the top.
Nice work. I've often wondered why the old lathes never had back splashes. I have one that fits on the chip pan of my logan. Doesn't look near that nice though.


Also made a bracket for the VFD to mount to the foundation wall next to the breaker box. The holes at the bottom are for standard electrical fittings:
a strain relief for the power cord on the input side, and flex conduit for the wires to the lathe.
DSCF7178_zps0qdl68vu.jpg
Click to expand...
 
My "light bar" is only a light support bar. It's a 20 inch long piece of 1 x 1 angle iron that bolts to the two unused bosses on the underside of the drive box frame. It's positioned parallel to the bed. Hopefully it will end up as a "light and chip guard support bar".

With a little luck, a few well placed cushions might help avoid a nasty rattle.
 
Sounds good. I never thought to use those bosses on the drive box: the holes for my bracket were already there. Your setup would be a bit more rigid I
would think.
 
GENTLEMEN: START YOUR ENGINES



A new 220V single phase outlet, a enjoyable session of concrete drilling :), a few trips to the hardware store and the VFD was mounted to the foundation wall next to the lathe and wired up. Programming the Mitsubishi
unit turned out to be fairly easy: I found the manual online and figured out the basic settings without too much trouble. Because the VFD was purchased used, I checked a number of settings to see how the
previous owner had it programmed and had no problems. Instead of wiring in an on/off switch on the input side, I just used a plug and a power cord. Motor direction turned out correct the first time. Success!

One question I have is what minimum and maximum frequencies you guys are using. I left the upper frequency at 60hz and the bottom at 30hz. I was under the impression that too slow a speed
can over heat the motor. I might run the math and see how the speeds come out at different belt settings and see how much range I need. Suggestions?
 
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What vintage is the motor? When I had the motor from my "new" lathe in getting new leads installed, the tech warned me not to very too far off 60hz. But, I have (I believe) the original 1963 era motor ... so old technology. Right or wrong, it made sense, so I have the VFD locked at 60hz. Not an issue since I have the reaves drive.

I tell you what though, I sure find myself changing speeds much more now that I don't have to stop and change the belts around. Changing the flat belt was no big deal, but for some reason I never liked changing the V belt pulley.
 
The motor is a NOS Dayton model 31TT08 that I bought on eBay. I checked before I bought it: that model has VFD rated windings in it, so I think I'm OK. I did run the math last night on speeds
at 55, 50, 45, 40 and 30 Hz. At 30 Hz I'm just duplicating speeds available at different belt settings, so I threw those out and made up a table of numbers that will live next to the lathe for reference.
I also discovered that I get a fair amount of vibration in the lathe at 60 Hz, but if I back it off to about 57 Hz it largely goes away, so I guess that will be the top end of the range for me.

Is the reason you don't change the V belt due to being tight on the pulleys?
 
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Nogoingback said:
Is the reason you don't change the V belt due to being tight on the pulleys?
Click to expand...
That and a bit of laziness I guess. And maybe just how I had things laid out as well.
It sounds like you have things covered pretty well with speeds. Between the three flat belt ratios and tweaking the VFD, you should have a bunch of options.
 
Yup, I should have enough speeds with this thing. The LAST task before I can make some chips is to finish up the drive box by pressing a new shaft
into the countershaft pulley and assembling it all up. Can't wait...
 
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