Knurling tool

[JasonBModerator @jasonb]

Posted by not done it yet on 11/08/2021 10:32:47:

As an aside.

……………………………………..

Do we have a lover or mate of RDG among the moderators?

I think it was something else in the post that got it deleted but can't remember now. May well also have been one of many of yours that get reported by various members so could be the problem is closer to home.

But if that was aimed at me then I have said in the past RDG are towards the bottom of the pile of suppliers I would go to and I'm not the only one who has said that. From my experience actually BUYING their products I would put them at a similar level to Amadeal and Chester, Warco a bit above that, Chronos & Gloster above that and then ARC, APT, Cutwel

[SteviegtrParticipant @steviegtr]

Posted by David George 1 on 11/08/2021 10:55:00:

Here is a video of my clamp type knurling tool. It has an additional bit that the rolled are offset to the left and so you can get nearer to the chuck jaws.

As I said previously if anyone wants a copy of the drawings just drop me a message.

David

That looks like a very substantial tool David.

Steve.

[Gary WoodingParticipant @garywooding25363]

Did you look at the link I posted at 9:47 on the 8th? (Mod edit the 4th)

Edited By JasonB on 11/08/2021 18:10:13

[SteviegtrParticipant @steviegtr]

Posted by Gary Wooding on 11/08/2021 18:04:20:

Did you look at the link I posted at 9:47 on the 8th?

Yes i did Gary & what a lovely job you made of it too. I did buy the Hemingway sensitive one. Which has now arrived. I will be starting it soon. I priced up all the materials , bearing in mind some stock is in longer lengths so some surplus. It came to around'ish the same as the complete kit with comprehensive drawings.

I will save your drawings though if you don't mind.

Steve.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, my curiosity about the tool Steviegtr bought, lead me to buying one myself and I have to say that his frustrations with this product are valid. Upon inspecting it, it does have a lot of side-play in the arms relative to the holder, this is somewhat due to the use of setscrews holding them in place, but also as there is a 0.27mm clearance between the arm clevis's and the holder, this can be reduced but not eliminated, by using bolts with a plain shank the length of the arm clevis.

I don't know about Steve's one, but mine didn't come with washers between the spring and the arms, this leads to the spring dropping into the small chamfer in the bolt holes and locking the whole thing in certain situations.

Adding a thin washer at both ends of the spring, prevents this locking up happening.

The next thing I noticed, is the bottom end of the bolt has a square edge to it, which also locks the tool when adjusting it down to it's smallest sizes, but also reduces the floating action somewhat, between fully open down to the smallest size.

My small scissor type bolt has a radius edge to it, which seems to stop this type of locking, happening.

Lastly, I don't think the shape of the dimple for the radiused top washer is quite the right shape or quite a large enough diameter, which allows the tool to kind of lock when using it with the arms on the two inner holes for using on smaller size diameters.

I did three samples with the tool, the first one from left to right in the photo below, was with the setscrews in place and was done on a piece of trued up black steel pipe, which is about 33mm diameter on the outside, the second one was done on a piece of 25mm EN8, but the set screws were replaced by plain shank bolts and the third one was done on a piece of 25mm unleaded mild steel, all of these were with the washers in place at each end of the spring. I think the worst result is on the mild steel one, but it can be clearly seen that the side-play in the arms move the knurl's out of line with each other in the opposite directions. I think it is clear that this tool does need some reworking done on it to make it a satisfactory tool to use and it may mean making a new holder to reduce the clearance in the arm clevis's and bespoke clevis pins to reduce the slop in the holes that hold the arms in place. Whether one thinks it is poorly made or not is up to the individual as it does work, but certainly not to a high spec.

Regards Nick.

Edited By Nicholas Farr on 15/08/2021 09:34:16

[Tony Pratt 1Participant @tonypratt1]

Nick, absolutely typical of most far eastern 'tooling', all the elements are there but so poorly executed as to make the tool completely unusable as purchased.

Tony

[SteviegtrParticipant @steviegtr]

Careful Nicholas. You'll be getting the same roasting as me. Yes i fitted 2 washers. Yes i also have a shorter spring for thin rod.

I was told it may not be the tool at fault. ??

Steve.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Steve, I spent two to three hours on Friday evening examining it in a logical and methodical way before I even attempted using it, the set-screws were the first obvious fault followed by the lack of the washers, I've seen set-screws used in similar situations during my maintenance years and it always caused slop and fast wearing of the clevis and the yoke holes. I was not biased by anybody's opinions in my assessment and if it had no faults and could be used to what I think was an acceptable standard, I would have said so and I will stick by that, whatever anyone says.

Regards Nick.

[VicParticipant @vic]

The clamp type Knurling tool I bough some years ago was also pretty poor, I can’t remember the vendor. Both the arms were a poor fit and very wobbly. I ended up making my own which works pretty well. I noticed the other day though that the Axles were worn so I made some new ones.

[Bryan Cedar 1Participant @bryancedar1]

I may have missed in a posting as to whether the ARC Euro knurling tool is recommended as they usually satisfy themselves that what they sell is fit for purpose.

[not done it yetParticipant @notdoneityet]

Posted by Nicholas Farr on 15/08/2021 11:27:30:

Hi Steve, I spent two to three hours on Friday evening examining it in a logical and methodical way before I even attempted using it, the set-screws were the first obvious fault followed by the lack of the washers, I've seen set-screws used in similar situations during my maintenance years and it always caused slop and fast wearing of the clevis and the yoke holes. I was not biased by anybody's opinions in my assessment and if it had no faults and could be used to what I think was an acceptable standard, I would have said so and I will stick by that, whatever anyone says.

Regards Nick.

Nothing wrong with telling the truth – as you see it. Well, not until a complaint gets the post(s) removed.🙂

[EmgeeParticipant @emgee]

Posted by Vic on 15/08/2021 12:06:06:

The clamp type Knurling tool I bough some years ago was also pretty poor, I can’t remember the vendor. Both the arms were a poor fit and very wobbly. I ended up making my own which works pretty well. I noticed the other day though that the Axles were worn so I made some new ones.

The clamp type knurling tool I use was made by a now passed toolmaker, although there is a fair amount of sideways movement (slop) of the arms in the yoke it doesn't affect knurling, even if traversing to obtain a greater width of knurling, the saddle moves and eventually when the play is taken up the tool head follows.

I believe you have identified an important point which is the accuracy of fit of the knurls on the pin and within the working end of the arm.

Emgee

[SillyOldDufferModerator @sillyoldduffer]

Posted by Emgee on 15/08/2021 14:24:15:

Posted by Vic on 15/08/2021 12:06:06:

…

The clamp type knurling tool I use was made by a now passed toolmaker, although there is a fair amount of sideways movement (slop) of the arms in the yoke it doesn't affect knurling…

…

Emgee

Emgee's post and my experience suggest sideways slop doesn't matter much, and why should it? Correctly adjusted knurl wheels follow their own grooves and the forces keeping them on track are considerable. The tool doesn't depend on being well made. Clamp knurlers are an inexpensive solution to an ordinary problem, not high-end production tools. Are chaps assuming clamp knurlers are precision instruments?

The acid test is for a few dozen members to each knurl several samples of EN1A rod and submit them anonymously with no clue as to how they were made to an independent panel. Only if the panel score statistically better than guesswork how the knurls were made is the case proved. Believers in 'quality' should be aware few sacred cows survive this test, whether it be fine wines*, violins, or Hifi systems. The problem is personal opinion and experience are both deeply unreliable. In the absence of objective testing, whatever you and I think constitutes 'quality' is probably unsound.

On a large sample I don't think a panel would be able to separate out well-made from ordinary clamp knurls. They would be able to tell the difference between cut knurls and clamp knurls, because cut knurls are almost immaculate. If you need reliably perfect knurls, don't mess with clamps – they're all mildly faulty. Cough up for a Cut Knurler and do the job properly!

Dave

* One test showed professional Wine Judges forced to rely on taste alone were unable to tell the difference between Red and White Wine…

[Nicholas FarrParticipant @nicholasfarr14254]

Posted by SillyOldDuffer on 15/08/2021 16:13:21:

Posted by Emgee on 15/08/2021 14:24:15:

Posted by Vic on 15/08/2021 12:06:06:

…

The clamp type knurling tool I use was made by a now passed toolmaker, although there is a fair amount of sideways movement (slop) of the arms in the yoke it doesn't affect knurling…

…

Emgee

Emgee's post and my experience suggest sideways slop doesn't matter much, and why should it? Correctly adjusted knurl wheels follow their own grooves and the forces keeping them on track are considerable. The tool doesn't depend on being well made. Clamp knurlers are an inexpensive solution to an ordinary problem, not high-end production tools. Are chaps assuming clamp knurlers are precision instruments?

Cut

Dave

* One test showed professional Wine Judges forced to rely on taste alone were unable to tell the difference between Red and White Wine…

Hi Dave, If you have ever had anything to do with rotary kilns, you will know that skewing the support rollers will alter the tracking of the kiln depending which way one or more rollers are skewed. The fact that the knurls on the tool in question have a helical pattern, they will act as is if they are skewed to the bar being knurled, but because the bar is relatively unmoveable, the knurls themselves will be forced in opposite directions, whether there is any slop or not, but yes, once the knurl has been formed they will follow there own grooves.

The photo below shows the tube that I did and it can be seen that the edge of the knurl close to the chuck only has the pattern of the top knurl in the tool for approximately 2.4mm, which is the same amount of slop of the two arms that can be moved away from each other by hand when set apart at the width at which the tube was knurled at, the bottom one moved away from the chuck and could be seen just beyond the end of the tube. The direction the knurls were force apart, followed the laws of skewing with the relative direction of rotation of all three rotating parts and the corresponding angle of the knurl patterns.

Regards Nick.

[SteviegtrParticipant @steviegtr]

Ah so i am not the blithering idiot i am porported to be.

Steve.

[VicParticipant @vic]

All I know is that the bought knurlier with the wobbly arms wouldn’t produce what I thought was a reasonable result and the replacement tool I made did, using the same wheels. Spooky coincidence maybe but I continue to use the one that works.

[Graham MeekParticipant @grahammeek88282]

A while back in this post I outlined the faults with the commercial knurling tools. Nick's photograph above clearly demonstrates what I said, a picture paints a thousand words.

Given the time so far expended on this discussion and the steps necessary to correct the faults with commercial knurling tools. To my mind it is easier to start from scratch with a known and proven design, and not necessarily mine.

As regards spending loads of money for state of the art knurling tools which only get occasional use, (even in the Meek workshop). To me this does not make financial sense, but each to his own. The only time I have found the more expensive knurling tools of benefit is when knurling Brass. As they produce a crisper pattern in this material. The manufacture of ones own cut knurling tool is no big deal, the knurls are a tad on the expensive side though.

I have attached photographs of the work produced from my meagre home brewed kit. The only cost of this standard of work is, financially for the knurls, and my time in making the equipment. The materials came from the scrap box. When I put this tool in the tool post I have the satisfaction of knowing that I made it, and more importantly it will produce the goods. The reliability of my knurling tool to produce good quality work first time has more than repaid for the time expended in its manufacture. "Does exactly what it says on the Tin" comes to mind. Click on the photographs for a closer look.

Regards

Gray,

[EmgeeParticipant @emgee]

Looking at the picture Nick posted I have experienced the same but only when traversing the knurls to get a greater width of knurling, The second point I made in my earlier post was regarding the fit of the knurls on the pins and fit between the spindle yoke, these are important and what I believe lead to a good working tool.

I remember years ago there was an article in ME about calculating the correct diameter for a given knurling operation, although I believe it is a good method I tend to give another 1/8 of a turn on the nut if the knurl doesn't look as required, it usually works OK.

Emgee

[pgk pgkParticipant @pgkpgk17461]

I haven't read that article but Tom's Techniques has a discussion of such calculations based on diameter of material and knurl tooth count. It struck me as a tad pointless since it's a distraction of metal rather than a cut such that any calculation would have to involve the depth of knurl teeth and an allowance for the proportion of distraction to remainder to calculate the circumference at the root of the knurled result.
I also just give the knurls an adjustment until it looks right.

pgk

[DMBParticipant @dmb]

I have in the past, ended up with knurling like what Nicholas Farr shows above. I am quite sure that NF and most others would do the same as me; curse then turn down the LH end of 'single knurl' in his photo, to remove same. What's left near enough perfect and no one else any the wiser.

I have bought knurls from various sources to fit a couple of clamp types. I am also making up one to Guy Lautards instructions as well. Frustratingly, not only do various sources supply different widths of wheels but the spindle holes vary in diameter, so nothing interchangeable.

John

[not done it yetParticipant @notdoneityet]

Posted by DMB on 16/08/2021 13:13:11:

….

I have bought knurls from various sources to fit a couple of clamp types. I am also making up one to Guy Lautards instructions as well. Frustratingly, not only do various sources supply different widths of wheels but the spindle holes vary in diameter, so nothing interchangeable.

John

John,

Apart from obviously needing different spindle dims for different sized knurls, the means of accommodating these different bores is to arrange for different sized holes on each side of the tool – one being the minimum and the other being the maximum spindle sizes required. Shims/spacers can be used to accommodate the knurl widths – as long as the tool is built for the maximum width. Knurl width could be reduced by grinding?

[Clive FosterParticipant @clivefoster55965]

As usual Graham Meek is right on the money.

When it comes to knurling half the secret is a decently made tool and the other half a respectable quality set of sharp knurls.

Personally I can't be doing with tools that need nursing. With due consideration to the intrinsic difficulty of the task of course. I want stuff to just work. If it doesn't it gets fixed or binned.

Although it is generally pretty true that knurls tend to follow their own path so sideplay and other sloppiness does not necessarily preclude the tool from cutting a decent knurl this does assume a proper start to the knurling with well defined tracks. A sloppy tool will generally be insufficiently stiff to get a good start so one, or both knurls fail to track properly.

Push knurling always requires a firm, quick engagement between knurl and work to get things started. Even on a decently hefty machine this can be difficult. My Smart & Brown 1024 and P&W Model B are both, by any standards, hefty and solid but you can feel the flex when starting a conventional "two knurls on a pivot mount" tool. Nervous or gentle engagement pretty much gets you nowhere. A decently stiff workpiece is also essential.

The Pratt & Whitney version of the push knurler with underslung pivot is noticeably better behaved than the usual symmetrical pivot version. Starting is more reliable and the tool works fine with less aggressive engagement. I put that down to the inline knurl starting first so it lays down a pattern for the underslung knurl to work into. Hence only one knurl has to cut into a solid, unbroken, surface reducing the forces needed as the second knurl pretty much only has to cut into the material raised by the first one. If the pivot is a bit stiff and the material soft its actually possible to make a single knurl with the in-line one before increasing the feed pressure a touch bringing the second one into play.

I suspect that many of the simple screw down clamp style knurlers have difficulty generating enough force to be truly reliable on more obdurate materials. Grahams version undoubtably delivers more push than the standard design. When using the lever operated sensitive feed on a Marlco for the first time it can be something of a surprise just how hard you have to push on the lever to get the knurling going.

I remain convinced that the hand squeezed 3 wheel nutcracker type is the most suitable and easily made tool for anyone who just wants to produce nice knurls. When things misbehave squeezing a little harder soon teaches them manners! I suspect the larger version published in Practical Mechanics may be a little easier in use than mine due to the longer handles. I feel mine is made to take material larger than its really happy with. Still works well enough at maximum size but I ned two hands to reach. But my hands are small.

Like pgk pgk I've always found the stock diameter calculations an unnecessary complication. On all but the smallest of work the diametrical difference for one knurl tooth error is inconsequential. Different for cut knurls where the process is more akin to gear generation so starting at the correct size becomes desirable.

Clive

[pgk pgkParticipant @pgkpgk17461]

Again most of these issues are resolved with a frame based knurl clamp and the knurl carriers are so simple that it's no chore to knock up a bunch for any knurls of weird width or spindle bore – assuming the tool was built to accept the maximum size and max anticipated diameter

pgk

[Graham MeekParticipant @grahammeek88282]

As regards calculating the required diameter for a specific knurl.

In the past this has been ridiculed as un-necessary. I for one have never done this. Because over the years I have come to know what diameters work with my knurls.

Our Continental Cousins however take a different approach. On page 92 of  the "Mechanical and Metal Trades Handbook", (Europa-Lehrmittel), there are seven different calculations which relate to 5 different types of knurling. These are covered by DIN 82 (1973-01). Clearly they have gone about the issue with some applied science.

The next time I have some knurling to do I shall give this a try.

Regards

Gray,

Edited By Graham Meek on 16/08/2021 17:55:14

[clivelParticipant @clivel]

Gray,
Some years ago in a posting about your calliper knurling tool you mentioned that it was specifically for diamond knurls and that you preferred a push type tool for straight knurling and explained why.

Unfortunately, not only have I been unable to find the original post but I can't recall your reasoning either.

So, for benefit of those who did not see your original post, or, as for myself, those that have forgotten the details, I would appreciate it if you could repeat your reasoning.

Thanks,
Clive

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