Scissor knurling type tool
2422 forum posts
Being really cheeky here. I know it has been done to death, but the knurling tool i bought from a sponsor on here is . Well lets say a bit to be desired. So i looked at the scissor type knurling tool & that is what i would like.
The only ones i can find are from India, yes they are catching up. Unfortunately they do not look very good quality. So with that i would like to buy some stock & make one as a project. The cheeky part is does anyone have a cad drawing or even a pdf of one that i could cadge from.
|pgk pgk||04/08/2021 05:29:34|
|2553 forum posts|
Edited By pgk pgk on 04/08/2021 05:30:06
22602 forum posts
Have a look at Hemmingway's offering here
|David George 1||04/08/2021 07:10:35|
1810 forum posts
This is my version.
It will open up to about 2 inch and down to very small. I have drawn it up if you want a copy I can email it to you. I used a set of wheels from a push type tool and they are easily changed for all three types.
|Craig Brown 2||04/08/2021 07:53:14|
|60 forum posts|
I made the basic one from Hemingway and find it very good, was also an enjoyable build. I modified the size of the arms and pins to accommodate the more commonly available 3/8" wide wheels. I have used the tool on both a Boxford and a large Colchester at work with great success on both
|Martin King 2||04/08/2021 07:56:39|
|994 forum posts|
You may want to check out Toms Techniques on YouTube, he does a complete build series for a knurling tool:
|470 forum posts|
The Hemingway kit is based on the Marlco knurler which is the best of the lot imo. They aren't cheap but worth looking at.
|1502 forum posts|
Have a look at Knurl milling. Seems to put the least strain on the spindle.
|713 forum posts|
NDIY how do we know Steve bought the Knurling tool from RDG? I can see three sponsors who sell Knurling tools, Arc, Warco and Chester.
22602 forum posts
Also no mention that the tool is at fault, the type that just push against the work generally leave a bit to be desired which is what Stevie's problem may be rather than the tool's quality.
RDG are not even site sponsors
|Clive Foster||04/08/2021 09:28:08|
|3105 forum posts|
I have a genuine Marlco and can confirm that its absolutely the bees dangly bits. Hefty old thing so lifting it onto the lathe gives you a nice work out. The Hemingway design is virtually a perfect, albeit scaled down, clone so I can't see any reason why it shouldn't be just as good if well made.
The usual shop made scissors style tool is much simpler and easier to build but lacks of the brute strength of the Marlco. Setting knurling depth and applying cut force for reliable clean knurls is easier on the Marlco too. Generally the common type is up for ordinary jobs but the relatively unsupported pivoting arms can mutually twist on larger and/or more difficult material. The bigger the capacity the more likely you are to hit trouble. Up to 2" or so, like Davids, you'd have to be unlucky with material choice. Beyond that a bit of extra care in material selection becomes needful.
As ever you gets what you pays for. Whether in money or build time.
Regular forumites will know that I recommend the hand squeezed 3 wheel "nutcracker" style for casual knurling as putting least strain on a smaller machine and fastest to do the job. I still use mine regulariy for quickies when I don't want to bother setting up the Marlco. Big disadvantage is that doing a bunch of knurls exactly the same is unlikely. Close yes. Exactly probably not. I find skimming the ends to put a shallow ring above and below the knurl works fine to "exactify" the appearance of knurled head screws and the like.
Decent quality knurls are essential. I've bought from Zoro and found their offerings good and not unreasonably expensive. Can find half price or less on E-Bay et al but ... My Marlco came with what I can only imagine a cheapy set installed. Worked well enough until I showed it a bit of stainless which promptly wiped the teeth off one side of one knurl leaving it D shaped with a nice shiny flat! Forensic examination of the knurls revealed that quality was "less than good".
I suspect most of the disappointing, inexpensive, import knurlers would do much better if quality knurls were fitted and attention paid to pivots et al. All the three sizes on one swivelling head breed that I've seen could do with serious attention to the swivel which is invariably far too stiff. But when you get a complete tool for less than Zoro sells a pair of knurls for something has to give. I have an unusually configured Pratt & Whitney made knurler with a single pair of knurls in a swivelling head. The pivot is very free moving.
Edited By Clive Foster on 04/08/2021 09:28:52
|Gary Wooding||04/08/2021 09:47:58|
|968 forum posts|
THIS is a link to a PDF of one I designed and made many years ago. I also designed and 3D printed a storage box for it and some additional knurls.
|John Hinkley||04/08/2021 09:48:04|
1310 forum posts
I've mentioned this before on the forum, in another thread, but I'll repeat it, anyway. I made a knurling tool to a Graham Meek design and it's very good indeed. That is to say the design is good, not necessarily my version. The design is detailed in Graham's book "Projects for your workshop, Vol.1"
It mounts directly in the QCTP and is easily adjustable from the front of the machine and can accommodate quite large diameters of material. I would second the advice to buy good quality knurls, too
As you can see, it works on the scissor principle, thus removing the thrust on the lathe bearings.
|Rik Shaw||04/08/2021 10:47:34|
1480 forum posts
Steve - I made one in 2014 and posted details here:
8509 forum posts
Joining the dots, I guess Steve refers to a bump-type knurler;
(Or the variant with two wheels.)
These are a poor choice for a small weedy lathe like a Myford, or a Chinese hobby machine of similar size. They require more sideways force than small machines can take. Steve doesn't want a better quality knurler, he needs a bigger lathe!
Scissor type knurlers are good for small machines because much of the force needed to squeeze knurls is provided by the balanced clamp. Not necessary to be a gorilla with a big lathe to make them work. Their disadvantage is they take more time to set-up than the bump-type.
Not necessary for a knurler to be well made. All it has to do is hold the wheels in more-or-less the right place. Knurling wheels don't have to run particularly true. However, as they take a fair hammering the wheels should be tough, otherwise the edges deform, rapidly wear out and spoil the knurl. Replace the wheels, not the whole tool.
I use an ordinary inexpensive scissor knurler, admittedly mostly on brass and aluminium, and it's fine after seven years. The wheels show no sign of wear yet. Not the best tool for production knurling steel, but 'good enough' for most hobby purposes I think.
For production work, the scissor knurlers are far from ideal - too much time wasted setting them up, and the knurls aren't of the best. For excellent consistent results, you need a Cut Knurler and a big machine:
The Dorian item illustrated above is yours from MSC at reduced price - only $1129.13
Dare I remind everyone again that engineers avoid the word 'quality' like the plague. In the absence of purpose, specification and value 'quality' is utterly meaningless. Other mindless words can be substituted:
Provided tools are fit for purpose and value for money, excess quality is irrelevant, as is where they are made. You do of course have to define what 'fit for purpose' and 'value for money' mean in your workshop. Anything less thoughtful is lazy, because unless money is unlimited we have to navigate between 'too cheap' and 'too expensive'. Professional engineers are highly cost conscious. For hobby purposes, I find mid-range stuff from reputable UK suppliers mostly acceptable, send the odd item back if it's no good, and never chase 'quality' unless there's specific need for it.
Being an old cynic I reckon most 'quality' tools in a home workshop are placebos. The job could be done just as well with ordinary kit. But whatever makes you happy!
Edited By SillyOldDuffer on 04/08/2021 12:52:18
|not done it yet||04/08/2021 13:21:50|
|6744 forum posts|
Because he posted that he had ordered it. I expect it arrived. I expect he has used it. I expect he has found it wanting…
edited to add what steviegtr actually wrote on the forum in a recent thread, which I found by searching for ‘knurling’
“By the way i have just ordered one from RDG tonight Clamp type , knurls up to 33mm. £19.95.”
Edited By not done it yet on 04/08/2021 13:27:08
2422 forum posts
Yes i did buy from RDG tools. I had a bit of fettling to do with it & it works just fine. The reason i want to make a better designed one is.
The one i have is very hard to tension the jaws. The ratio is not great. Also the tensioner is very near the rotating work & bothers me a tad when tensioning because of the effort needed to turn it. The Meek design caught my eye with the tensioner at the back.
I also thought it would be a nice little project to do. Thanks for all the comments & answers as always.
Edited By JasonB on 04/08/2021 16:07:55
|John Hinkley||04/08/2021 16:28:05|
1310 forum posts
I thought that I'd posted a correction to my post earlier, but must have forgotten to press the "Add posting" button, so .....
I erroneously credited Graham Meek's design to his book "Projects for your workshop". Although there are a couple of incidental pictures of it in there, it was in fact published in Engineering in Miniature. Volume 35, issue 5 (November 2013), and possibly subsequently in further editions of his "projects" series books.
Apologies to Graham and Steviegtr for the wrong information and any confusion caused.
Humble pie for dinner tonight.
|Craig Brown 2||04/08/2021 19:07:57|
|60 forum posts|
I'm assuming you are trying to apply tension with the knurls on the stock? The way I use the scissor type tool is to set the tool so the wheels just drag the stock at the top and bottom then move the carriage off the work then apply some "cut", start the lathe and bring the wheels back onto the work (a good chamfer on the stock helps here). I have always had good success this way
2422 forum posts
Yes Craig i could do that. Although i have seen the one by Graham Meek & i like that idea. Guess i will have to buiy his book to get the drawings for it.
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