Hobbymat lathe - couple of questions

Hi D and Martin, really appreciate the information, and noted (copied into the growing file..)

All those dims are very useful and I have no intention of going metal of any kind on the gears, but obviously I will need t either buy OE or buy different thickness material to blank and cut. Cheers Chris

I would slow down a bit before ordering steel plate to make the t-slotted plate to decide if it is useful. It looks like the plate is intended to bolt to the angle plate - see the 4 holes in the plate that are used for holding the vice. However you might as well just drill a pattern of holes in that side of the angle plate. T-slots can be a bit of a pain as they are never where you want them and the t-nuts slip out of place, Nice M6 threaded holes are much better behaved.

Have another look at the minilathe gears as the centres may not need modifying. Since mostly the gear fits on a boss you can just make a suitable smaller one, Look at the dog clutch on the leadscrew where one gear fits - probably can make one to fit the minilathe gears. That only leaves the one to be fitted to the back end of the mandrel that needs a 20mm hole so only a few need to be of that size and perhaps can be printed. (see the other thread on 3D printing.

Hi Chris the plate is actually 27mm thick, but I don't think it matters too much how thick it is.

Bazyle makes some good points about machining the existing boss / bosses on the hobbymat to suit the mini lathe (or similar) change wheels. And a flat plate drilled and tapped to suit your equipment is also a good idea.

But if you are going to machine new wheels from blanks, a piece of 10mm thick Acetal sheet (or Delrin) 700mm x 90mm should provide enough material for all the change wheels in my photo. It's easily sawn into square pieces and will give enough extra to trepan out the discs for the wheels. This doesn't include the ones fitted on your lathe.

And a piece that size will cost about £17 + postage (UK)

Ian

Just noticed the time on my last post is 23:23:23 couldn't do that again even if I tried!

Hello Chris,

I've sent you a PM regarding set up gear trains for metric and imperial threading, others such as DP and Mod can also be set up readily

Regards

Brian

Bazyle, thanks for the advice, I will hold off T slotting, but may go with a plate bigger plate than base and tap M6 spaced out across the piece. Thanks also for reminder on mini lathe gears, I need to think about this and consider it better with matching boss.

Hi Ian, I've not seen acetal slabs that cheap, I'm obviously not looking hard enough

But I am going to slow down a bit and try and really work out best route per Baz.

On the mill plate... any reason why I could not use ally if its accurately drilled and tapped? - ok accurately by my standards Also also, I can't see how the mini vice would bolt up secure to the original plate unless I don't have the original mini vice.

Hi Brian, big thanks for this, I have just worked out how to find a PM.. I will send you a message - really appreciated!

Best Chris

THOUGHT

Are the gears for mini lathes Mod 1, and of similar dimensions?

If so, since the standard Hobbymat gears are stated to be "plastic", maybe it would be possible to obtain and modify gears for the two common manufacturers of mini lathes.

I think, subject to correction by those more knowledgeable, that Real Bull machines have a 4 mm keyway, and Sieg machines have a 3mm one

Gears for Sieg machines should be available from Arc Euro or Chester, probably ex stock, and possibly the only mod needed may be just enlarging the keyway, (with a file? ), or maybe enlarging the bore and remaking the keyway. This could be a way of obtaining the changewheels needed, rather than searching for costly hen's teeth.

Howard

WHY do I only spot the typos after hitting "Send"?

Edited By Howard Lewis on 03/01/2020 10:54:42

Some thoughts:

The lathe is still in production in the Czech Republic and Pro Machine Tools are the UK agents;

**LINK**

**LINK**

They may be able to help with change wheels.

If you can manage German this company also claims to offer spare parts;

**LINK**

I bought my milling head directly from Teco a few years ago I have not used the other two suppliers.

The normal milling set up is to remove the topslide, fix the angle plate to the crossslide, fix the topslide to the angle plate and then fix the vice to the topslide.

The plate is usually used with the milling head that bolts to the back of the lathe base (I believe that the original was aluminium)

Have just checked a 90T gear for a Sieg SC6, that I bought in for a project.

The teeth are 8.01 mm wide, and the central boss is 9.85 mm wide

The central boss is 24.89 mm in diameter.

The bore is 16.02 mm, with a 4 mm keyway.

This and others for the same lathe, or possibly for the SC4, may be suitable raw material for modification to suit the Hobbymat.

The gear is metal, so will be more expensive than a plastic equivalent, but a complete set may be cheaper, and easier to obtain, than the genuine article. You may think it worthwhile to enquire at Arc Euro Trade, if they can provide any help.

And in addition to any cost saving, the gears can be made exactly to fit your machine, in addition to providing either some practice, or some enjoyment, in their modification.

Howard

If you don't mind modifying the machine, then the advice to turn up new studs to carry the plastic gears from the SC2 or SC3 mini lathes is a good one.

The plastic gears will be cheaper than metal, and fairly easily available. But there is no 100T available, 80T is the largest supplied. I cut my own 100T gears when I wanted to obtain a finer feed on my SC3.

And if you ever want screwcut Imperial threads, you will need a 63T which is very likely to be metal.

The faa that the gears are from a lathe with a 1.5 mm Leadscrew is of no consequence. What matters is the ratio between the Mandrel and the Leadscrew.

A 1:1 ratio on your Hobbymat will produce a 1mm pitch thread, where the same set up on a lathe 1.5 mm pitch Leadscrew would produce a 1.5 mm pitch.

If you wanted a 1.5 mm pitch, you would need to set up a 1:1.5 ratio, such as a 60T driving a 40T on the Leadscrew, with any suitable gear between as an Idler.

Brian Wood's book, "Gearing of Lathes for Screwcutting" explains it. But in the chapter on the mini lathe, you will need to use mental arithmetic or a calculator to modify the numbers for either the charts for the 1.5mm Leadscrew, or the 2 mm pitch Leadscrew. The 2 mm chart is probably the easier since you have only to multiply or divide by 2!

Howard

Hi Chris. The standard milling table that Hobbvymat supplied is aluminium alloy, and the vise bolts length-wise to it, i.e. jaws parallel to slots.

If you want (or need) to use the vise with the jaws in the other orientation, it can be bolted directly to the topslide - using one mounting hole beneath the toolpost, and the other is the one between the toolpost and the back of the slide (if you wondered what it was for.. it's usually plugged with a slotted grubscrew) ..be mindful of the length of the bolts used - there's very little clearance between the upper & lower parts of the slide, and also, be gentle when tightening either the vise or the toolpost when fitting - the standard bolts have a shear groove in them to prevent overtightening (and bowing or warping the topslide)

Hi Howard, thanks for your input, I have no problem in fairly accurately enlarging a keyhole or bore so what you have posted would be good options (added to file )

I am inclined to stick with plastic for the gears for now though, or at least once commit!

I quite like this lack of spell check on the site, makes me write proper

Thanks Roger, I wil check out those suppliers, at least to get a cost comparison, I am guessing it will be spicy cost wise but you never know...

Thanks also for the description on the mull plate setup and cross-slide - I was being thick... all clear now - appreciated.

Many thanks D, this is very useful re the vice and particularly care on length of mounting bolts I need to make up. Noted thank you.

Chris, just a thought concerning the chuck jaw numbering which no one appears so far to have mentioned. Are all the jaws undamaged as far as the scroll teeth are concerned? I once bought a good looking Pratt Burnard chuck from 'Tractor Clear Out' event which had very little use - but I found that the 'thin' scroll tooth on No.1 jaw was broken, this meant that as it was now 'out of sequence' it was fitted last - so the fitting order became 2 - 3 - 1 rather than 1 - 2 - 3! Its worth checking.

My other thought is concerning making a T slot plate in steel - beware that the plate is liable to warp when you cut the T slots especially if the overall thickness is on the minimum side. Cast iron is far preferable from a stability point of view.

Best of luck with the machine - I hope you get many hours pleasure out of it.

Cheers Oily, it is a good shout. The chap I bought the machine from is a very savvy engineer and I would not expect him to have mis-ordered the jaws by mistake. I did put them back in numbered sequence and they did align well but will take off and check the jaw scrolls for any damage which I did not do, may even try an F1 chuck change time, down to 10 mins so far

On the mill plate & T slots, I am going to go for interspaced M-whatever threaded into an ally plate, I am hovering over a 25mm x 150 x 150 at the moment which I could reduce in outward width.

Per Baz I think the T slot design may not be that flexible & fiddly. Pic of the sort of layout I'm thinking of but much smaller of course. Pic of current face plate as I see that did not work previously.

Nice bike, need to add a pic of mine

Cheers

Chris

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<img src="https://i.ibb.co/8zX1mds/IMG-0395.jpg" alt="IMG-0395" border="0">

<img src="https://i.ibb.co/cLJ496H/s-l1600.jpg" alt="s-l1600" border="0">

That didn't work either zzzzzz

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Give up on the image posting

https://i.ibb.co/8zX1mds/IMG-0395.jpg

https://i.ibb.co/cLJ496H/s-l1600.jpg

Chris

Add some pics to your Album. Go to the top Menu and click Album, then add Pics and then use the Browse function to locate the pic in your computer to upload to your Album.
There is a camera profile in the Message header to add a pic from your Album to the message.

Emgee