Reduction gear for headstock?

[GrahamRounce]

Hi - I can't afford a variable frequency inverter for my 250W Record Power DML36SH-CAM woodworking lathe, but I would like to be able to run it slower.

I thought just a planetary reduction gear, say 4:1, between the shaft and the chuck (3/4" 16tpi) would do it. Obvs it would have to be quite heavy duty.

I'll keep Searching, but if anyone can suggest a source, or alternative, that would be terrific.
Thanks,

 

[flh801978]

If you could find a gearbox to do what you want it would be treble what a VFD would cost

 

[paulm]

Doesn't it already have four speeds, 450 to 2000 rpm ?

Curious what you want to be doing at less than 450rpm which is pretty slow for most things, maybe thread chasing or texturing or something ?

 

[Phil Pascoe]

I would think that anything requiring a speed lower than 450rpm would need more than 250w to drive it.

 

[GrahamRounce]

<Wipes off the douse of cold water>

Phil: If was geared down 4:1?

paulm: I'm working with acrylic. Specifically, a 40mm dia rod that I've part-drilled a 25mm hole through, using a flat bit.
Of course it well overheated, but I thought that running a side-chisel down the hole, to tidy the last 0.5mm or so would make it clean.
Unfort, the original overheating seems to mess up the acrylic deep down, and the side-chisel also overheats easily, and it's impossible to clean it up. So I thought, 'Avoid the overheating!" and started trying to think of ways to slow down the rotation.
I'm just guessing at about 100rpm.
I suppose I could interpose another pair of pulleys between the motor and the shaft, but that too is rife with practical difficulties.

flh: I suppose I was hoping for something junk/convertible!

Thanks,

 

[Phil Pascoe]

Is this a job you'll be repeating often? Is your tailstock 1MT or 2MT? Is the size of the hole critical?

 

[GrahamRounce]

Phil - Probably not! I've already gone to a lot of trouble with supporting the "rod" so it doesn't wobble, gripping the side-chisel in the tailstock to move it in slowly, trying different versions... Everything I try to do seems to go just beyond what's possible, at least for me! Moan.

 

[paulm]

Maybe the lathe is the wrong machine for the task, metal working lathe would be better of course, but absent that a pillar drill on lowest speed, hss twist drills working up from small to large and plenty of lube might do it. Of course you may well not have access to a pillar drill in which case ignore me ! Twist drills over about 13mm might be a challenge to find also, or expensive of course.

 

[Owd Jockey]

On the opposite end of the spectrum I recently got my Axminster Hobby converted so I could turn some large 20" od platters off the bed. It was expensive though £650+, using the Speed Genie from haydock converters I got a reversible speed controller and a new 1 hp motor , besides all the necessary brackets.
the system worked really well and I could turn some really heavy wet wood at 90 to 300+ rpm.

 

[Phil Pascoe]

£650+ would buy you a nice larger lathe.

 

[TheTiddles]

It’s not just the gearbox you’d need, you’d have to anchor that gearbox to the lathe, doesn’t sound practical, but nice alternative thinking

If you’re only doing it once, can you jury-rig a cordless drill to drive the spindle which will be way slower? Might struggle on power but if you’re slow it might just do it.

 

[Rorschach]

If you are drilling acrylic you need plenty of coolant usually.

 

[marcros]

I think that the flat bit is causing some of the problem. I am not sure what you mean by side chisel, but if it is a boring bar of sorts then it might work and is probably the way that I would go.

I have drilled acrylic for pen tubes- 10mm (ish) holes where surface finish is important. The key I have found is taking it slowly (lowest speed on the my wood lathe) and withdrawing every few mm to clear and cool. I also use a bit of vegetable oil as a cutting oil, put on the drill with a paint brush. it may take you a while, but...

Once affected by heat, I always found it very difficult to recover the piece.

 

[GrahamRounce]

The flat bit is all I have for >20mm. I knew it would make a mess, but expected that taking another 1mm off with a sharp side-chisel, done extremely slowly, would be ok. But no.
(I call it a side-chisel, home-made:

Don't know if it has a real name?
Yes, I should have used oil. I tried a cold air blower which seemed to cool quite well actually, but the result was still disappointing.

 

[GrahamRounce]

The Tiddles: Anchoring the support wasn't difficult.
I'd attempt a gearbox in the same way. Well, similar.

 

[Rorschach]

Washing up liquid and water is an excellent coolant and lubricant for acrylic.

 

[GrahamRounce]

Strange that my comment re Variable Frequency Inverters seems to have disappeared.
Browsing ebay, the prices seem to have come down a lot, to <100 or even <50.
But they are poorly explained and nearly all have a 3-phase output. Why? Could I use just one phase? Also, they have block-connectors for the connections, instead of a normal mains lead for In and a normal mains socket for Out, tho not too important.

 

[GrahamRounce]

Rorschach: Thanks!

 

[TheTiddles]

The Tiddles: Anchoring the support wasn't difficult.
View attachment 115662I'd attempt a gearbox in the same way. Well, similar.

That might work, you’d be removing any alignment you had and make the gearbox do that for you, plus the cantilever load.
Maybe a local fabricator could do it for you?

 

[Spectric]

Does it need to be acrylic, nylon turns very nicely.