Lathe for miniature turning

[Mr Ed]

I've done an operation similar to this making heads for thumbscrews, where I wanted to make a batch all in one go. Basically used the method Jason describes, the only difference being that I used a parting off tool to set out the wheel thicknesses cutting part way through and then a V shaped cutter to go into the gap left to make the chamfer, prior to finishing off the parting. I have a quick change tool holder so this method is no hassle, it would be a bit more inconvenient without. Jasons suggestion of a combined tool is a good one, but it can be done with individual cutters if needed.

On the subject of cutters, it is easier than you think to grind your own. I am new to this type of lathe work and got a box of toolsteel blanks with my second hand lathe when I bought it. Consequently I had a go at grinding cutters following instructions off the net and got good results almost straight away.

I found this website with some initial instructions on lathework generally quite helpful to begin with

http://www.americanmachinetools.com/how ... _lathe.htm

couldn't find a UK site with similar detail but that doesn't really matter.

Cheers, Ed

 

[Takazeki]

Very helpful tips! I had tought about that first option, cut half the way and they chamfer using that gap space. I specially liked your 3rd solution Jason and i found some great info in the site Ed pointed:

The v-shape groove seems to be what i need. But as it has a flat shape point, it won't cut through the rod (of course). Maybe, like Ed referred, i need to look for a v-shape cutter. I can't find them in the Unimat and Warco catalog's though.

In this early stage i'll work with 3 main materials: polyurethane, PTFE (teflon) and maybe nylon. After figuring what which one is the best i'll probably stick with just one of them.

I'll also left you with an example of the kind of wheels i'm seeking:

Regards

 

[Mr Ed]

Maybe, like Ed referred, i need to look for a v-shape cutter. I can't find them in the Unimat and Warco catalog's though.

What I was getting at in the second part of my previous post is that its quite easy to grind your own cutter to a profile to suit what you need. No need to find one, just make one.

Cheers, Ed

 

[jasonB]

As Ed says its easier and cheaper to grind your own from the HSS ones I linked to early on.

Having now seen the wheel I would suggest the set up below using three tools that will not need changing

1. Spotting drill diameter of hole, this will save having to use separate center drill and finish drill, they will be OK drilling 3-4mm deep in plastic

2. V tool with slightly rounded or angled point, this can be used to reduce the bar to finished size and also form 2 chamfers at once

3. Parting tool mounted upside down in rear toolpost, could use it in a front mounted quick change toolpost.

This would be the method

1. chuck a lenth of rod with 30-40mm protruding

2. use the side of the V tool to reduce 20-30mm of the rod to final diameter.

2. feed in the spot drill for say 20mm

3. feed in the V tool, this will chamfer the back of one wheel and the front of the next

4. feed in the parting tool to separate the wheel, first off the rod will only have one chamfer but the rest will be double chamfer

Repeat 2-4 to make several wheels then draw some more rod out of the chuck an dback to number 1.

You may want to think about Acetol as it turns better than nylon.

Jason

 

[Takazeki]

Nice scheme! I understood your idea but is that rear toolpost an extra accessory? Perhaps i can get the quick change tool post and easily switch between the v tool and the parting tool (although it's an expensive addon..)

Ok so to summarize, considering the Warco mini lathe (for example) datasheet here what accessories would you recommend me? #-o

Oh i remembered now another important thing. The wheels will take miniature bearings so backside hole should be narrower than the frontside hole (where the bearing enters). My idea is that i will need to make a hole in the rod with the diameter of the wheel's backside hole first, and then do the larger hole to a specific depth later, correct? The surface inside the wheels should also be smooth, will the spotting drill allow that?

I have a partner working with me, he's very well impressed as well with this forum so far! I'll make sure to engrave "UKWorkshop" in a piece of teflon as soon as i get my machine :twisted:

Regards

 

[Marco]

Hi!

If you are in Portugal I would get a einhell lathe! I have one...It's made by sieg. it's the 7X12 version...It comes very complete!

2 chucks... 3 jaws and an unusual 4 jaw chuck self adjusting! ( it's more precise than the 3 jaw..I've measured 0.04mm of runnout, the 3 jaw 0.08 to 0.1mm runout) both chucks come with reversible jaws.

It brings some cutters, 2 way tool post...automatic feed with extra gears.

Also have a live center, Faceplate, Steady Rest.

Costs 550 euros...and it's a lot beefier tan the proxxon! Proxxon it's kinda overrated and it's really small.

Good luck, I've been there and decided not to import.

Marco

 

[Takazeki]

Well, hi marco! (viva!) I saw the einhell lathe in Leroy Merlin a few days ago but i were kinda septic because einhell makes a lot of different stuff. I also didn't know it came that complete! The 3 jaw can be used as a drill chuck marco? Are you overall satisfied with the machine?

Regards

 

[jasonB]

MArcos suggestion of a local supplier may be the better option as I suggested earlier, I'm not sure if Warco will export, they definately wont send to Canada but Europe may be different.

The only extras you will need to add to the Warco one for making your wheels are a keyless drill chuck and the quick change toolpost as the rear mounted post will have to be made by you. Buy HSS tools from elsewhere

If you want a stepped bore for the bearing to register against the easiest way would be to use the spot drill for the through hole then cut the counter bore by end feeding a slot drill into the hole, this will be easier than using a boring tool or "D" bit

3-jaw chuck cannot be used in the tailstock to hold drills (but it can on a unimat)

Jason

 

[Marco]

The 3 jaw can be used as a drill chuck marco?

No, you need to buy a MT2 chuck...look for ebay uk I've bought a diamond chuck (Chinese] for a decent price and decent quality

Are you overall satisfied with the machine?

Overall it's OK, not a suisse precision machine

 

[Takazeki]

The only extras you will need to add to the Warco one for making your wheels are a keyless drill chuck and (...)

Won't the key type version also work? It's quite cheaper!

I think i had now understood the whole process, thanks all for the kind explanations and suggestions. I'll come back later, eventually with results

 

[jasonB]

Yes the keyless one will work but the keyless will be quicker to use thus reducing your production time now that you need to change between bits so it will soon pay for itself in the time saved.

If you really want to make a lot of these then converting the tailstock to lever action and using a turret head will speed things up

Jason