Knurling Tool for Mini Lathe

I realise that I need a clamp type knurling tool for a light weight Mini Lathe and I was wondering what people's experience has been of what's available. You can spend as little as £16ish from Axminster and over twice that from other sources.

I don't do 'heavy work' (well, you wouldn't, would you?) and would be unlikely to be knurling steel. Some names would be a great help. The Indian-made stuff I have bought really looks and feels pretty fair, in general and it would be good to have a UK distributor.

Andrew

Edited By andrew lyner on 12/04/2019 23:01:47

I would be a little suspicious of a tool that is half the price of the others , best thing you can do is go to the shop and have a look at it . Check for things like side play in the arms also if the knurling wheels run true and the teeth are nicely formed . Be wary of pictures of the tool as they can be made to make the tool look better than what the tool really is . The side play can cause problems when you want to do a long knurl as it allows the wheels to cock sideways and this can effect the finish . I have a knurling tool that came with my qctp and the wheels have so much run out they are more like little cam lobes than wheels !

You could also make your own tool and buy the wheels .

If only there were those shops around. It would take a day trip to visit any supplier that I know of. Cheaper just to buy blind.

I have made a few bits and bobs for my lathe but there are things I actually want to make with it and I can't be sure enough of my skills to be confident that what I made would be good enough. I could, of course, make it like a tank - as I do with most of my home made tools. No beauty pageant!!! And the materials would cost loadsamoney.

Hi Andrew have you thought if going to the exhibition at Doncaster there are always a few goodies to compare!

David

Doncaster's a long way to go, I'm afraid. I may be demonstrating my dilettante attitude to the business but I was hoping to get the benefit of the experience of others from this very useful forum from the comfort of my office chair. I would travel a fair distance to spend a few hundred quid, though.

He might be living in Australia for all his profile tells us!

Axminster and £ are a give away that he lives in the UK.

I'd be inclined to go for the £31 Axminster one, if the capacity of 25mm is enough.

**LINK**

The main failing of the cheaper ones is a flex, due to the thin shank.

Jim

Edited By jimmy b on 13/04/2019 09:24:53

Hi Andrew, I bought the top one in **LINK** many years ago and has been OK Warco sells the same type also.

Regards Nick.

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Edited By Nicholas Farr on 13/04/2019 09:39:52

I just got back indoors from feeding the kangaroos and read this. Usual sloppy thing about filling in my profile but I do worry about the dangers of this new fangled internet. Risks and benefits, you know. Essex is where I live, since moving back from Wogga Wogga - I really miss those dingos.

That RGD tool in the link does look a bit flimsy and the ones on eBay here, look more substantial and a bit bigger. Has anyone tried one of those? The useful gap seems to be a bit under 40mm, which would be good if it's not too wobbly. It has the right size shank for me and there are extra wheels. The 50mm Warco one looks less substantial from the picture but someone mentioned the problem with relying on pictures.

I can't help much with respect to current commercial offerings but many years ago I made one to a design from the ME. This uses a nut to apply pressure to the knurling wheels and whenever I use it I am suprised at how much pressure is required to achieve the depth of cut that I want. So my thoughts are how effective are the styles shown in these links, is it easy to apply sufficient pressure with a knurled knob as opposed to a spanner on a nut?

Phil

Mine has flats cut into the knurled knob for a spanner. Never had to use a spanner for aluminium or brass, and only rarely on steel. However I use the tool in a particular way. Clamping slightly off-centre means the wheels can be pushed into the work by the slide as well, allowing the cutting pressure to be adjusted under fine control. No idea if this is right, but it works for me. The pressure applied by the slide to an offset clamp is much less than needed to cut with an ordinary knurler.

Dave

Edited By SillyOldDuffer on 13/04/2019 12:01:54

Might help to choose a knurling tool if the maximum diameter that could be knurled was stated in the advert, not based just on shank size, poor information from suppliers.

Emgee

andrew

If you are able to make your own tool the three wheeled, hand squeezed, "nutcracker" type is more appropriate to a mini lathe as the lathe only has to handle rotational forces. The various fits and alignments are a little less critical too as the tool tends to settle itself in alignment with the job regardless so small errors.

The fundamental issue with conventional knurling is that considerable forces are required which are essentially independent of the size of the machine. Inevitably a big, hefty, machine is much better able to handle the loads than a small mini-lathe. When it comes to stiffness size counts double. Doesn't help that a mini-lathe size knurling tool has to be smaller to fit so its inevitably less stout. To work reliably the pivots and arms should be closely fitted with minimal shake which is hard to do at a price the typical min-lathe user can afford. A decently made tool fitted with good quality knurls can work quite well but this is definitely not a place where low bid rules. All other things being equal shorter arms are better. There is a picture on an earlier thread of one with nice short stiff'n stubby arms.

Don't know if you can still get them but my two P&W, underslung pivot, push type knurling tools have narrowed knurl faces. The wheels are the usual 3/8" (ish) width but the actual knurl part is only around 1/8" wide, plus a bit for edge chamfers. The forces involved are much less than that needed with a conventional tool. Partly due to the underslung pivot and partly due to the narrow knurls.

Clive

Edited By Clive Foster on 13/04/2019 13:29:23

The Ebay one looks worth a chance

Jim

Edited By jimmy b on 13/04/2019 13:51:11

I decided to go for the eBay one. I'm sure it will be up to anything I want it to do. My Warco Lathe is doing very well but I still have trouble with getting a good finish. Still learning about sharpening tools correctly, though, so I put it all down to that. The quality of my knurling will probably be at least as good as the rest of my work.

Thanks for the views, chaps.

My first knurling tool was made from a flint wheel from a BIC ciggy lighter, all that was needed was a bit of scrap steel, a bronze bush in the wheel, and a needle roller out of a bearing. Made it about twenty years ago, and it still gets used. If you feel that side pressure is not on, I'm sure that a clamp type tool could be made. The pattern is of course parallel rather than diamond. Sorry the photo;s a bit dark.

Ian S C

I ordered the eBay tool (scissor type) and it is quite heavy duty. It seems to have some lateral movement but, once the wheels have started to bite, it works fine (so far).

I still don't understand how the system works actually. The feed speed, the diameter of the piece and the pitch of the wheel lines all seem to 'cooperate' to give good diamonds. Is it to do with the lateral movement that the tool seems to allow?

I read one post on this forum that claimed the ratios had to be calculated first etc. etc. but others just pooh poohed the idea.

I've just had a play with knurling, based on ideas from this webpage.... http://conradhoffman.com/knurling.htm

I tried doing some knurling "off the cuff" and of course it came out rubbish!

Followed the detail on Conrads page, and worked out the pitch of my knurl to be 1.233mm (ish)

Turned my test piece down to 11.77 mm from 12mm, and it cut nice!

Hope this helps someone