Got the RF 30 Mill - Cheap Lathe Question

I bought the RF-30 mill. It was cheap enough, but I was hesitant about whether I would get any use out of it, but then I figured its got to be better than either of my drill presses and the price was a lot less than any good drill press. The seller threw in some tooling and an old 8.5 by 18 HF

31316 lathe to get me to close the deal.

I figured out the basics of the mill pretty quick. Its biggest limitation is the rigidity of the quill. It is way better than either of my drill presses and still quite a bit better than the cheap mill drill I use as a "better" drill press. However at full extension I can feel atleast a few thousandths deflection with the quill locked. A couple quick runs with a face mill on aluminum pretty much confirmed this from the fair finish quality. Basically its exactly what I expected. The vises, mills, several chucks, several collets, clamping set, etc were a nice little bonus.

About the "free" lathe.

I didn't think a whole lot of the lathe, but figured it had to be worth a couple hundred bucks. Its not bad, but not great Somebody must have worked on it at one time because the center line of the chuck is pretty close to parallel with the ways. The tailstock is adjusted pretty darn close too. There is where the good news ends.

The pulley's were jacked around for maximum speed. I think two of the pulleys are actually reversed on the shafts to give greater speed increase. Its enough that it bogs down the motor on startup. It claims it only has a

3/4 HP motor, but once it gets going its unstoppable. I mean it will hog a .06 deep thread in one pass in 1" aluminum rod. Badly, LOL, but it does it. (its way to fast for thread cutting the way it is.)

Anyway, the speed was jacked up to use it for wood turning. I know because everything was full of sawdust.

If anybody has one of these things I'ld sure appreciate a picture of the pulleys and belts, and the size of the belts. They are certainly not the original belts if I am correct about the pulley setup. The way they are now its impossible to slow the machine down enough to do real (or surreal) metal work.

The next bad news. The saddle itself is sloppy on the ways. The ways themselves don't look bad or even worn, but the way to adjust the saddle is not immediately apparent. I'm sure I'll figure it out eventually, but a scan of the original manual or atleast the exploded parts diagrams would sure be nice.

More bad news. Some of the threads listed in the gear chart are impossible to cut. No kidding. If I try to install the gears for one thread I tried I found one gear would not reach the threading drive gear, and the other was so big it would hit the pulley. I think somebody figured out the ratio when it was originally built and never bothered to check if the gears would fit. LOL.

One small bit of good news. After I got the compounded apart, sawdust cleaned out, relubed, and reassembled it I found its slightly more rigid than the mini lathe. Of course that doesn't help until I figure out how to tighten up the saddle on the ways.

Pictures? Manual? Anybody?

I already posted on CNCZONE in the manual section, and on the 8x18 lathe group on Yahoo.

Now for a scary thought. I'm considering CNCing it, but in a way to retain manual operation. LOL (it really is better than the mini lathe in some ways)

Reply to
Bob La Londe
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jsw

Reply to
Jim Wilkins

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I bought the RF-30 mill. It was cheap enough, but I was hesitant about whether I would get any use out of it, but then I figured its got to be better than either of my drill presses and the price was a lot less than any good drill press. The seller threw in some tooling and an old 8.5 by 18 HF

31316 lathe to get me to close the deal.

I figured out the basics of the mill pretty quick. Its biggest limitation is the rigidity of the quill. It is way better than either of my drill presses and still quite a bit better than the cheap mill drill I use as a "better" drill press. However at full extension I can feel atleast a few thousandths deflection with the quill locked. A couple quick runs with a face mill on aluminum pretty much confirmed this from the fair finish quality. Basically its exactly what I expected. The vises, mills, several chucks, several collets, clamping set, etc were a nice little bonus.

About the "free" lathe.

I didn't think a whole lot of the lathe, but figured it had to be worth a couple hundred bucks. Its not bad, but not great Somebody must have worked on it at one time because the center line of the chuck is pretty close to parallel with the ways. The tailstock is adjusted pretty darn close too. There is where the good news ends.

The pulley's were jacked around for maximum speed. I think two of the pulleys are actually reversed on the shafts to give greater speed increase. Its enough that it bogs down the motor on startup. It claims it only has a

3/4 HP motor, but once it gets going its unstoppable. I mean it will hog a .06 deep thread in one pass in 1" aluminum rod. Badly, LOL, but it does it. (its way to fast for thread cutting the way it is.)

Anyway, the speed was jacked up to use it for wood turning. I know because everything was full of sawdust.

If anybody has one of these things I'ld sure appreciate a picture of the pulleys and belts, and the size of the belts. They are certainly not the original belts if I am correct about the pulley setup. The way they are now its impossible to slow the machine down enough to do real (or surreal) metal work.

The next bad news. The saddle itself is sloppy on the ways. The ways themselves don't look bad or even worn, but the way to adjust the saddle is not immediately apparent. I'm sure I'll figure it out eventually, but a scan of the original manual or atleast the exploded parts diagrams would sure be nice.

More bad news. Some of the threads listed in the gear chart are impossible to cut. No kidding. If I try to install the gears for one thread I tried I found one gear would not reach the threading drive gear, and the other was so big it would hit the pulley. I think somebody figured out the ratio when it was originally built and never bothered to check if the gears would fit. LOL.

One small bit of good news. After I got the compounded apart, sawdust cleaned out, relubed, and reassembled it I found its slightly more rigid than the mini lathe. Of course that doesn't help until I figure out how to tighten up the saddle on the ways.

Pictures? Manual? Anybody?

I already posted on CNCZONE in the manual section, and on the 8x18 lathe group on Yahoo.

Now for a scary thought. I'm considering CNCing it, but in a way to retain manual operation. LOL (it really is better than the mini lathe in some ways)

Reply to
Carl Ijames

Thanks. I appreciate that.

Reply to
Bob La Londe

Thanks Jim. Maybe, except this one does not have a quick change gear box and many of the newer models do. Thanks for the link.

Reply to
Bob La Londe

FWIW, most of the small import lathes can cut many more thread pitches than are shown on labels or in manuals. Then, there are some improvised/alternate gear combinations that are within a RCH of being right on the nose (sniff).

I put a pdf file in one of the old dropbox archives which shows many pitches for the popular 9x20 lathe models, so if your machine is a kinda-sorta copy, and you have the same gears to select from, you're in good shape there.. not too important though, I guess, if you CNC it.

There are likely to be Yahoo groups related to the RF and clone mill models, so someone may be able to steer you to groups for your new machines.

Reply to
Wild_Bill

I'm going to have to find that. Remember where I should start looking?

I was thinking that, but every once in a while I will want to "feel" what I am doing I suspect or thread something quick without waiting for the computer to boot up. Then it mighbt be faster to wait for the computer than to change gears. LOL.

There are a number of RF-30 conversions out there, but I was thinking about leaving it manual. I've already got the Taig and the Max NC for small stuff, and the Hurco for big stuff. The biggest thing I might do to it is see how I can improve the quill. Then again I might CNC it, but set it up to be manual as well. For now its staying manual.

Reply to
Bob La Londe

I noticed you mentioned your new lathe doesn't include a QCGB, and I thought: Oh, wunnah those. Still, there may be a Yahoo group, or someone that knows about the headstock gearing and leadscrew size/pitch etc.

I'm not so swift with the math required to do the gear ratios/leadscrew pitch math.. so I just mount a dial indicator and count the spindle rotations to double-check the setup before committing to chip cutting.

The 9x20 models have the gearbox, but here is where a chart can be found in the 2004 archives..

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Link to other comments in RCM archived messages can be found by searching for.. Expanded threading chart for 9x20 lathes NOPOL

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Reply to
Wild_Bill

"Wild_Bill" wrote

If the spindle and leadscrew turn at the same speed the lathe will cut the leadscrew's pitch. For other threads the gear-up or -down ratio equals the pitch ratio. Finer threads require a slower leadscrew so it gets the larger gear.

For example my leadscrew has 8 threads per inch. To cut 3/8-16 the leadscrew has to be reduced to half speed with 2:1 ratio gears, like 48 and 24 or 64 and 32, whatever fits.

jsw

Reply to
Jim Wilkins

Yep.. see what you're sayin' Jim, although on my larger machine, there is a

2-range speed selector in the headstock for changing between fine and coarse leadscrew feeds (plus a stack of change gears, but no QCGB). So, there's the additional gear ratios, and trying to mentally sort it out on the fly is a bit overwhelming for me anyway.

Luckily for me, I had the pleasure of communicating with a very sharp participant named Ted Edwards, in the old days here on RCM, and he had written a program to simplify any pitch that the SOG stack-o-gears is capable of.

I'm a bit hostile toward software, and respect those who can use it to solve problems or create easy solutions for the not-so-bright-ones such as myself.

Reply to
Wild_Bill

You deal with the fine and coarse feeds by assuming they are two interchangeable direct-drive leadscrews of appropriate pitch. An 8 TPI leadscrew geared to half speed is equivalent to a 16TPI one driven at spindle speed. It might be easier to think in terms of how far the carriage moves per spindle rotation, half of 1/8" is 1/16" in this case.

My South Bend has a spindle-speed 40 tooth gear on the tumbler stud driving a 56 tooth on the gearbox input through an 80 tooth idler. I have no idea what some of the gears in the box are, I only know that when I set it to cut

8 threads per inch the 8 TPI leadscrew and the spindle turn at the same rates.

The threading chart was missing and I had to reconstruct it from a barely legible photo.

The left-hand lever clearly doubles the threads per inch with each step, starting at 4TPI and ending at 256. The right-hand one's progression was less evident as some positions cut standard threads at only at one left+right combination, like 11-1/2 and 27 TPI for pipe threads. The top row of my chart is 4 4.5 5 5.5 5.75 6 6.5 6.75 7 7.5

When I bought the lathe I was making optical components which are all metric. I entered the coarsest right-hand-lever thread pitches given above into the columns of a spreadsheet and made the rows progressively double them, corresponding to the positions of the left-hand lever. Then I tried several combinations of metric transposing gears to see if multiplying all the cells by the transposing gear ratio of N/127 gave useful optical thread pitches. 100/127 is South Bend's standard but I had more hits on the finer pitches with 120/127.

jsw

Reply to
Jim Wilkins

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