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Knurled Tool

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oskar

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#1
Looking for suggestions on a knurled tool for my Taig mini lathe with a tool holder capacity 1/4” to 3/8”. Would like to make some knobs for small screws.

Searching I noticed they also come with several wheels with different patterns which will be nice
 

FLguy

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#2
Look at Sherline they have a small knurling tool that ought to work well for you. I have one on my Sherline 4400 lathe am happy with it.
 

oskar

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#3
Found it at Sherline, looks pretty good, thanks
 

mikey

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#4
I own the Sherline knurler and it works. However, it is nowhere near as good as a scissors knurler. The problem is that nobody makes a good scissors knurler for the Sherline/Taig sized lathes so I made my own by looking at a single blurry picture of a knurler made by Chris Heapy of the UK. Maybe these pics will be enough to get your thinking going:

IMGP0566.jpg IMGP0565.jpg IMGP0581.jpg

All mild steel, aluminum spacers, aluminum mounting block. Knurls are from FormRol, pins are drill blanks. There is zero play between the plates and arms but the arms move freely; it is extremely rigid. Capacity is 1/8" to 2-1/4" OD. It will knurl everything we commonly work with, from plastics to brass to steel to stainless steel. It mounts solidly to the Sherline cross slide with two T-nuts.

I do not have plans for it but can give you details if you have questions. I will tell you that there is no comparison between this knurler and the Sherline tool.
 

British Steel

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#5
Agree with Mikey, scissor knurlers are way better, particularly on small lathes - the "bump" knurlers that just run in from the cross-slide put a lot of force back into the toolpost and don't engage as positively - you can get scissor knurlers to fit in the toolpost slots though, or you may be able to remove the bar and replace it with a piece of suitable key stock to clamp in the TP?

Dave H. (the other one)
 

oskar

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#6
Thanks Mike for your time and definitely it’s a project I would like to do. I found the FormRol site which is very good with tons of information plus I found a .PDF document about Knurls which I will read to educate myself.

No need for plans but I have these questions:

What is the approx. overall size of the main block?
What is the size of the main bolt? Are the threads coarse or fine?
What is the size of the knurls you have?

Much appreciated
Nicolas
 

FLguy

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#7
Mikey that knurler looks very similar to the one Hemingway Kits from the UK sells. I made a larger sized one on that design for my big lathe. It's a joy to use.
 

Ken from ontario

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#8
I don't know what happened to my post here.
 

Ken from ontario

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#9
Dave ,Mikey, thank you both for your replies, I read them in my yahoo mailbox (that's where I usually receive notifications for all my my threads/post) but they disappeared from this thread after the quick upgrade this afternoon.
Mikey, now that you explained how the knuckles are secured,I can see the grooves clearly.neat idea bytheway ,the whole project looks very well machined and precise. the one I'm working on is quite sloppy compared to yours but after all it is inspired by my other Chinese knurling tool which (surprisingly) works exceptionally well.
 

oskar

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#10
There are some post missing here, can this be corrected?
 

mikey

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#11
Yeah, can this be corrected? If not, I'll re-do my responses if I can remember what I said ...
 

Nelson

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#12
That likely occurred during the migration from the old to new server. Sorry about that.
 

mikey

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#13
That likely occurred during the migration from the old to new server. Sorry about that.
Okay, no problem, Nelson. We'll just respond again. Thanks for looking into it.

Mike
 

mikey

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#14
Thanks Mike for your time and definitely it’s a project I would like to do. I found the FormRol site which is very good with tons of information plus I found a .PDF document about Knurls which I will read to educate myself.

No need for plans but I have these questions:

What is the approx. overall size of the main block?
What is the size of the main bolt? Are the threads coarse or fine?
What is the size of the knurls you have?

Much appreciated
Nicolas
I'm gonna' try to remember what I said the first time but if I miss something, ask, okay?

The mounting block is 6061-T6; 2-1/4" front to back, 1-1/2" high, 1-1/4" thick. The mounting block places the centerline of the knurler on the centerline of the lathe behind the work piece. The bottom of the knurler plate registers on the edge of the cross slide and when the screws are locked down into the T-nuts in the cross slide, the entire knurling tool is solidly held and cannot turn or move unless you want it to. Some users feel that a slight angle of the knurls toward the headstock is desirable; I have not found this to be necessary.

Contrast this to the Sherline tool, which is intended to be mounted loose so the base of the tool can move. Presumably, this is to allow the knurls to track better. My results suggest that a solidly mounted knurler with tight tolerances will form a more precise knurl with very little chance of mistracking if everything is done right.

The main tension screw is 12L14. The threads were 1/4-28 on top with a class 3 fit into the top nut. The bottom thread inserts into the half-moon insert with a 1/4-20 thread, Loc-tited in. 12L14 is more than adequate for this application because there is not an excessive amount of tension on the stud. Over the years, it has performed flawlessly with no sign of wear.

Knurls are from FormRol, 1/2" OD X 1/4" thick X 3/16" ID hole. These knurls are from the EQ series (1/4" wide) instead of the EP series (3/16" wide EPR/EPL 230) that Sherline uses. The knurls I used were the straight EQ 230 pair (fine pitch to reduce mistracking), EQR/EQL 225 and EQR/EQL 230. I had them custom grind a bevel on both sides to allow for axial running and they work well for that.

All knurls above are Circular Pitch knurls. I do not use Diametric Pitch knurls and do not calculate diameters; I just crank down to achieve about a 90% pattern depth and run the knurl. Note that FormRol considers anything deeper than a 90% pattern to be over-knurling that can damage your knurls. These are HSS knurls but I've done a fair number of knurls in stainless steel and have noted no significant wear. If I were to do a lot of it in SS though, I would use cobalt knurls and maybe switch to carbide pins.

Unasked for info:
  • Side plates are 1/4" thick mild steel.
  • Arms are 5/8" mild steel, milled square to 1/2" X 1/2" X 3" long.
  • Top nut is 12L14 steel.
  • Delrin washer underneath top nut
  • Half-moon inserts are 1/2" OD, O-1 tool steel left in annealed state. No point in hardening them when they run in mild steel with very little movement.
  • Aluminum spacers are ~3/8" OD.
Hope this helps, Nicolas.
 

mikey

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#15
@Ken from ontario wrote:
Mikey, I got a question for you, the pins that hold the knurls, how are they secured so they don't become loose and slide off? I'm working on modifying a bump type knurling tool and for the pins I used SH cap screws with lock nuts ,I like your approach better, it looks cleaner , I have lots of drill rod to use but as I said I'm worried in case the knurls would slide off during the operation unless they are slip fit.
Oskar, I'm sorry for posting this question in your thread but it is something you may encounter yourself if you decide to build the tool from scratch.


Then Dave (@British Steel) nailed it:
Hi Ken,

I may be wrong (Mikey won't be!) but the 2 SHCS visible on the scissor arms look like they have washers under their heads, and those could fit in a groove in the pins, locking them in place?

Dave H. (the other one)


I will respond again for the benefit of those who come later and expect an answer.

The pins are 3/16" drill blanks, not drill rod. They have a shallow slot cut on one end. A stainless washer has a flat ground on one side that fits into this slot. A 6-32 SCHC locks the washer in place. This holds the pin solidly but allows for very quick disassembly for cleaning. I got this idea from one of Guy Lautard's bedside readers and it works well. Drill blanks are hardened and the slots were cut with a Dremel abrasive wheel.

pin2.jpg pin1.jpg
 

ddickey

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#16
That's pretty much exactly how I did mine. I also lapped the pin in the hole for the knurl.
 

oskar

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#17
Thanks Mike for your time and the detailed description. BTW your knurled tool looks more like a piece of art than a tool, its amazing!

I will never achieve such a workmanship with my limited skills however I will try to make a workable tool.

Nicolas
 

mikey

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Thanks Mike for your time and the detailed description. BTW your knurled tool looks more like a piece of art than a tool, its amazing!

I will never achieve such a workmanship with my limited skills however I will try to make a workable tool.

Nicolas
Thanks, Nicolas, but its just a tool, done with care. You CAN do this. If you like, PM me and we can work on it together.
 

oskar

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#19
Thanks, Nicolas, but its just a tool, done with care. You CAN do this. If you like, PM me and we can work on it together.
Much appreciated Mike, finishing now a QCTP and when this is done I will start the knurl tool. Have to order some material and I will contact you when needed.

BTW trying to order the the drill blanks from KBC tools but they dont show the length and when I called the guy said its "Jobbers length" but did not know the actual length. Anyone knows what length is "jobbers length"?

Since I'm in Canada I try to order locally and the knurls available are as per attached picture. I choose the 25TPI/50T. Is this acceptable or another choice will be better? I only work with aluminum
http://www.kbctools.ca/customer/kbtoin/customerpages/digitalcatalogs/cmaster.htm#book/281

Nicolas
 

ddickey

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#20
Did you ordered the knurl pins also.
 

oskar

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#21
Just realised I didn’t include the picture in my last post, its attached here

No I didn’t order the knurl pins yet because KBC provides steel pins for $3.25 or Carbide pins for $19.10 and the drill blanks are $2.95.
 

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mikey

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#22
Big knurls, Nicolas. You might consider a 1/2" OD knurl instead.

Re the pins, how do you envision securing them to the arms? That will determine which material to use.
 

oskar

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#23
They only have 3/4" OD, I will call and find out if they can get me 1/2" OD

I was thinking to secure the knurls to the arm like you did but my arm will be made with 1/2" thick aluminum. I prefer not to use steel since I only do hobby work and aluminum is much easier to mill.
Nicolas
 

mikey

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#24
I would use mild steel if I were you but its your call. Knurling involves pretty high forces, though, so maybe think about it. Mild steel is not difficult to mill and it will hold up better over time. Also bear in mind that the modulus of elasticity of steel is three times that of aluminum.
 

oskar

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I would use mild steel if I were you but its your call. Knurling involves pretty high forces, though, so maybe think about it. Mild steel is not difficult to mill and it will hold up better over time. Also bear in mind that the modulus of elasticity of steel is three times that of aluminum.
 

oskar

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#26
Hi Mike

I understand your concern about the mild steel but it’s only about a month I have my mini lathe and never used a lathe before so I’m hesitant to use steel right now. If all goes well later on I can replace the aluminum knurl tool with one made out of steel. I only have a hobby shop which is equipped for woodwork and I cut aluminum to size using a Miter saw and Skill saw with a 50 tooth carbide blades. These blades work well on aluminum but are not good for mild steel.

The knurls I want to make are to replace some 8-32 and 10-32 SHCS on my mini lathe and I will make them out of brass or aluminum with a diamond pattern. Which pattern do you like better between the ones you bought (EQR/EQI 225 or 230) and do they produce a diamond pattern?
 

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#27
Both are good. The 230 is a finer pattern than the 225. I don't have a lot of pics of knurls so I keep showing the same ones.

Here is one in aluminum with the 225 knurls:

IMGP0578.jpg

Here is what is called a square knurl, done with a pair of 230 straight knurls and a pointed HSS tool ground to the same angle as the knurl's teeth. You cut the straight knurl, measure the distance between the peaks, then cut perpendicular lines to the same depth and pattern with the HSS tool. Makes for an interesting pattern. Not my idea; this came from Geo. H. Thomas.

IMG_3880.JPG

The 225 is just slightly coarser than the 230 but the difference is noticeable. If I had to pick one, I would choose the 225.
 

oskar

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#28
Thanks for the pictures Mike, those knurls look pretty sleek

I got in touch with Form Roll Die and they can ship to Canada. They gave me a price of $13.35 for each of EQR 225 & EQL 225 and I plan to order them on Monday. I will also ask them if they can custom grind a bevel on both sides on each knurl like you did and if not too expensive I will take it.

I will also order 2 drill blanks 3/16” from KBC in Canada. Do you know if FormRoll can also supply these drill blanks? If yes I might as well get the set from them.

Nicolas
 

mikey

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#29
I decided to take a look to see if anybody made a knurler that would work on the Taig without you going through the trouble of making one and I found this: http://www.cartertools.com/lmsk.html

Here is the knurler: https://littlemachineshop.com/products/product_view.php?ProductID=1911

Cost is not too dear and it would get you up and running quickly. Rather than making a knurler from aluminum, I would consider the one from LMS instead. Later, when you are more confident of working with steel, we can re-visit making a knurler if you like.
 

oskar

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#30
Mike you are amazing and thanks for your time again

It’s funny because I visited cartertools site many time before but I missed that page. It’s also interesting because a similar tool (picture attached) is selling in a town close to mine.

In any case I apologise if I sound stubborn but I prefer to make my own and the main reason is to gain the experience using my lathe. If the results are not good, then I will buy either the one you mentioned or the one close to my town.
 

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