Supplier of quality knurls?

[Ed DuffnerParticipant @edduffner79357]

[Ed DuffnerParticipant @edduffner79357]

Afternoon all,

Other than RDG, Chronos and Ebay can anyone please suggest a UK supplier of good quality 3/4" dia' x 3/8" wide x 1/4" bore 14tpi LH / RH knurls? I'm hoping not to have to sell a kidney to buy them.

I bought a pair of Raizo knurls from Ebay but the LH one had a manufacturing flaw, the replacement sent was a RH in LH packaging. No response from the seller the second time around when I asked for another replacement. But that's my problem. Tried to use what I had but found the LH is also not concentric, runs like a cam.

Thank you,
Ed.

[Roderick JenkinsParticipant @roderickjenkins93242]

I've bought similar knurls from Gloster – they seem to be good quality (when I looked earlier today I could only see straight knurls in their ebay shop -curious)

Rod

[CirclipParticipant @circlip]

Tracy tools?

Regards Ian.

[James BParticipant @jamesb]

Hi Ed,

Cromwell Tools list that size – 3/4" x 3/8" x 14" – in straight, right hand, left hand and checkered patterns.

James

Edited By James Burden on 29/05/2015 12:25:24

[Ed DuffnerParticipant @edduffner79357]

Thank you guys for the additional pointers.

Regards,
Ed.

[Ed DuffnerParticipant @edduffner79357]

I managed to get some 14tpi knurls from two different suppliers in the UK. Both 3/4" diameter. One has 32 teeth at 25°, the other has 28 teeth at 30°. Using the 32 tooth pair I did some tests and the knurl pattern is too large. I've tried some finer (16tpi) knurls but the pattern is too small, so I require some in between (goldilocks) knurls!

Looking more closely at the original pattern using an online knurl calculator and some measurements I'm now convinced the knurls I need are metric, 1.7mm (14.9tpi) pitch with a 40° angle. Can't seem to find metric pitch knurls anywhere other than a company called Accu Trak and those available are either 30° or 45° and not 1.7mm pitch.

I've written to Accu Trak and another company to see if they can suggest anything or a possible alternative. I also noticed on a couple of other forums' threads pulled from google searches, references to 15tpi knurls in the USA ? which might do at a push, but again it's finding a supplier.

Ed.

[Ed DuffnerParticipant @edduffner79357]

I was just wondering if I could make a straight tooth 90° knurl with 1.7mm pitch and cant it to 40°, make the impression, then cant it to 40° the other way for a second pass? would that work in brass or would it be too work-hardened for the second pass?

Ed.

[VicParticipant @vic]

I get the impression that industry doesn't use crush knurling very much these days but use cut knurling instead. As a result I guess most of the knurls commonly available have been specifically made for the amateur market? Having said that I did manage to get some rather nice Swiss or German made knurls at the Guildford show a couple of years back. I've not made a holder yet for them though as the bore is 6mm rather than the usual 1/4".

Edited By Vic on 03/06/2015 19:55:56

[Neil WyattModerator @neilwyatt]

Posted by Ed Duffner on 03/06/2015 19:04:13:

I was just wondering if I could make a straight tooth 90° knurl with 1.7mm pitch and cant it to 40°, make the impression, then cant it to 40° the other way for a second pass? would that work in brass or would it be too work-hardened for the second pass?

Ed.

I would try it, I reckon it would work and canted knurl needs less pressure.

As knurling is normally only decorative, I assume you are trying to match some existing parts?

Neil

[pgk pgkParticipant @pgkpgk17461]

No idea on cost but if you google 'special order knurls' there's a few co's making them…..

[Ed DuffnerParticipant @edduffner79357]

Hi Neil, Pgk,

Thanks for the encouragement. I'm trying to reproduce some brass knobs which are volume and tone control knobs for a vintage guitar made in Japan. I apologise that this is not model related. I will get around to making a German loco at some point in the future.

I had some very helpful info from a gentleman at Accu Trak and also an offer of assistance from a British company. I also had a quote of $250 for one set of special knurls

I have drawn out the 40° knurl pattern in CorelDraw with a spacing of 1.7mm vertically(across each diamond point) as it would be viewed in the lathe, known as the transverse pitch measurement to the knurling manufrs.

This then gives me a 1.30mm measurement from groove to groove at 90° to the groove (normal pitch). I've just received some silversteel from the posty so will have a go at this today.

Q: Hardening Silversteel. One online source suggested coating the part in soft soap before heat treating to reduce the scaling caused and make it easier to re-polish between heating. I only have a butane blow lamp. With the info from the web and this forum would my following process be ok?

– Polish the part.
– Coat parts in soft soap.
– Heat to cherry red and quench in water or oil
– When cool, re-heat to straw colour and quench again.

 

Regards,
Ed.

 

Edited By Ed Duffner on 05/06/2015 12:20:15

[Michael Cox 1Participant @michaelcox1]

Hi Ed, Soft soap will reduce scaling but not eliminate it entirely. You will probably need to re-polish the knurls after the quench. It is only necessary to re-polish one side of the wheel in order to see the colour change.

Alternatively you can temper in a bath of hot oil at a controlled temperature and no polishing would be necessary.

Mike

[Roderick JenkinsParticipant @roderickjenkins93242]

Ed,

I would quench into water from carrot red (cherries come in all sorts of colours!), I don't think distortion will be an issue for knurls.

As far as tempering is concerned, what you are trying to do is to get the whole thing to the same temperature, which is about 240 degrees C for straw coloured. You need to allow a little time for the metallurgical transformations to take place. I recommend using a bed of sand. A small metal tray ( a jam pot lid will probably do) with some sharp sand in it. Bury the knurl in the sand so that you can still see the surface colour and then gently waft a flame under the tray so that you can see the colour slowly develop. Heating needs to be very gentle so that you don't over heat. Quenching is unnecessary after tempering, it is better to let the job cool slowly.

HTH,

Rod

Edited By Roderick Jenkins on 05/06/2015 12:08:34

[Neil WyattModerator @neilwyatt]

> I apologise that this is not model related. I will get around to making a German loco at some point in the future

Please DON'T apologise!

You need to clean the part, or at least some part of it, to see the tempering colours.

I temper small parts in the oven at ~ gas mark 6 which gives me a nice nice deep straw (your oven may give different results…), but for knurls which need to be very hard and don't have shock loads, sneak them into the deep fryer next time you make chips*

Neil

*That's fries for our transatlantic readers.

[Ed DuffnerParticipant @edduffner79357]

Thank you chaps, I didn't realise the tempering was so gentle. Instead of sand could I use brass chips I've collected from the lathe? I 've seen it used by watch makers on youtube for tempering spring steel.

I've double checked my measurements and found the normal pitch is 1.3mm. I can always make another if I get it wrong.

Here's a drawing of the working out.

Regards,
Ed.

[JasonBModerator @jasonb]

Have you looked at MSC, 3 pages of various knurls though it looks like standard metric pitches are 0.4, 0.5, 0.6, 0.8, 1.0, 1.2, 1.5 and 2.0. 1.5 would be 16.9tpi

Imperial fine 0.025, med 0.04 and coarse 0.057

[John HinkleyParticipant @johnhinkley26699]

Ed,

You could try the French site: Otelo.fr search for "molettes". They stock three types, all 19mm diameter with 1/4 (6.4mm) bore, to give fine, medium and coarse diamond patterns, although they don't quote a specific pitch. They won't cost a kidney, though you may have to sacrifice an arm or leg – under a fiver each, but they quote a tenner for postage!

John

[Ed DuffnerParticipant @edduffner79357]

Hi Jason and John , thank you for the web site pointers. I did find MSC but I don't think they do the one I'd need, no worries. Doing this project has been a bit of an eye opener. It seems that although there are standards(fine medium, course) , the different suppliers have their own spec and it's a bit of a gamble as to what you actually receive through the post. I also found a Malaysian supplier but no luck there either.

I'm in the process of making a knurl maybe two from some 20mm silver-steel. Just got in from the shed, lost track of time! Have been making a 48 hole index plate to enable single cut broaching of the knurls.

Ed.

[Ed DuffnerParticipant @edduffner79357]

Started to make the custom knurl yesterday. It's taken about 4 hours to broach almost half way around the 20mm silver-steel. I must be mad! Here's a photo, plus a couple more of the basic indexing setup.

Ed.

[Ed DuffnerParticipant @edduffner79357]

I managed to get to the end of the broaching and it seems to have gone ok . From the original 19.96mm diameter I lost about .08mm in the process and the knurl meshes into the pattern on the original parts quite nicely.

Had my first go at heat hardening since I was in school and It's taken three attempts to get a hard surface. I don't know about cherries and carrots but bright orange is what I would call it. A file just about makes a faint scratch on the surface.

For tempering I don't have sand but I tried brass chips in the earlier attempts and the colour change just kept going after removing the heat and it was still soft metal. Would it be ok to use a hot air rework station for electronics to temper the part? (it has 100-400°C range) …and how long does the part have to be held at 240°C ?

Regards,
Ed.

[Roderick JenkinsParticipant @roderickjenkins93242]

That looks very smart. Tempering – 1 hour per inch of thickness is the usual rule of thumb so you probably need half an hour. In this case a domestic oven is probably your best bet but I don't see why the hot air station shouldn't work if you can set the temperature. Our oven goes up to 250C but I wouldn't like to say how accurate this is and in which part of the oven. I'd set the oven (or hot air station ) to a lower temperature and then gradually raise the temperature until the colour looks right.

Good luck,

Rod

[Ed DuffnerParticipant @edduffner79357]

Thank you Rod, I'll give the hot air station a go then as my oven is 230C max.

Regards,
Ed.

[Ed DuffnerParticipant @edduffner79357]

I tempered the knurls to what I think is a straw, not having seen it done before. The one on the left has been tempered and re-polished with an abrasive block.

…and have been in the groove this afternoon and evening making a few knobs with the knurls.

Very happy with the result. I need to make a new holder for just one knurl and do each opposing angle separately as there is not enough room for the clamp knurling tool and a live centre. Job for tomorrow!

Six parts ready for broaching and marking.

Thanks again for all the help and advice.

Cheers,
Ed.

[Roderick JenkinsParticipant @roderickjenkins93242]

Splendid knobs!

Rod

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