Lathe advice

cannon monkey · Wed Sep 21, 2011 12:50 pm

Say I own one Of these but needs a motor where could I start lookin for a cheap fair price on a motor for something like this

ramses · Wed Sep 21, 2011 8:42 pm

Treadmill motor, but you'll need a DC motor controller. Then you'll have infinitely variable speed.

Otherwise, search google for "induction motor" and your voltage and frequency (120 vs 240v, 50/60 hz)

jackssmirkingrevenge · Wed Sep 21, 2011 11:47 pm

Alster370 wrote:Ive currently been using the one first one on the left for a cutoff tool, im guessing its the wrong one right?

Have a look here.

Alster370 · Sun Sep 25, 2011 11:36 am

Ive had my lathe for about a week now, and although I haven't done much lathe work on it yet, i have noticed it is definitely short on torque for work on steel materials. So I think to myself, what could I do to improve it?

Replace motor?
Replace belt wheel for larger one?

But then I stumbled across this site: http://www.varmintal.com/alath.htm#Slowing

It clearly shows a torque potentiometer on the circuit board. I've gone and took some pictures of my lathes Circuit board and there are indeed 3 potentiometers, the only trouble being which ones are which. There is a pair of them at one end and one on its own at the other end of the board. So im guessing the two are low speed/high-speed and the other one is torque? Im not going to harm my machine indefinitely by adjusting them am I?

Labtecpower · Sun Sep 25, 2011 12:22 pm

How much steel do you "feed" it?

If I want a nice finish I feed a maximum of 0.1-0.05 mm

For normal cutting jobs in steel we feed about 0.5-1 mm, but that is on a
4 KW lathe.

Alster370 · Sun Sep 25, 2011 1:09 pm

This is related to specifically, parting operations on a 10mm steel rod. There is just too much friction from the tool sides rubbing on the work piece. It took the best part of an hour to cut though it, and this is with a very very slow feed rate. Its fine for facing and finishing though, just takes a bit of time.

Labtecpower · Sun Sep 25, 2011 1:32 pm

It took the best part of an hour to cut though it

That's not OK. How about cutting it off with a saw and face it? I do it that way and it saves quite a bit of time.

ramses · Sun Sep 25, 2011 2:21 pm

Alster370 wrote:This is related to specifically, parting operations on a 10mm steel rod. There is just too much friction from the tool sides rubbing on the work piece. It took the best part of an hour to cut though it, and this is with a very very slow feed rate. Its fine for facing and finishing though, just takes a bit of time.

You need to relieve the sides to cut down on friction. Cut it so the tip is just a little wider than the sides. Bits that have a "T" shaped cross section are reported to work well. Some grind a sharp "V" in the top to facilit chip breakup.

Here.

Technician1002 · Sun Sep 25, 2011 2:46 pm

Another option on parting tools is to anneal the tip, hit it with a hammer to shorten and thicken it, re temper it, and grind a new cutting edge. This makes the cutting edge slightly wider than the rest of the tool.

Like a saw blade with offset teeth, the cut must be wide enough for the rest of the tool.

Alster370 · Sun Sep 25, 2011 3:17 pm

I might have a go at that, sounds pretty easily unlike grinding your own cutting tools

.I agree, These tools are pretty mediocre and no manual! I have been able to machine some pen gun parts very easily, so Il upload that when im done. This lathe is surprisingly accurate for a handmade machine

ramses · Sun Sep 25, 2011 3:26 pm

Arguably, it's harder. It's my understanding that HSS likes to de-carb.

All you need to do to the existing bit is grind a tiny bit off each edge to make it shaped like that described.

Also, you could make two overlapping groves, so the tool has more clearance and can't bind.

velocity3x · Sun Sep 25, 2011 5:15 pm

Alster370 wrote:It took the best part of an hour to cut though it, and this is with a very very slow feed rate. Its fine for facing and finishing though, just takes a bit of time.

What spindle speed are you using? Actually, it should only take a few seconds. Personally, I'd part 10mm mild steel about 600 rpm's with a generous supply of oil from a brush.
Also check the parting tool height.

Alster370 · Mon Sep 26, 2011 10:52 am

IF the tool was 2mm below the centre, would that affect, friction and cutting capability? Because ive only noticed yesterday that my tool needed risers to get it to centre height

inonickname · Mon Sep 26, 2011 11:05 am

Alster370 wrote:IF the tool was 2mm below the centre, would that affect, friction and cutting capability? Because ive only noticed yesterday that my tool needed risers to get it to centre height

It'll wear your tool in funny ways and reduce cutting efficiency and result in poor finish. You can set the tool slightly low (or high perhaps) for a different cut but it's a tiny amount..as small as you can do effectively. 2mm is far too much.

Alster370 · Mon Sep 26, 2011 11:12 am

I thought it was really bad to have it above the centre line? You either have it on centre or very slightly below it?

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