Knurling tool build

rwm

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It was very difficult to machine all these parts to get optimal spacing for the knurl wheels. My original idea of a hollow axle with a screw through it solved that issue and was workable but not ideal. It required partial disassembly of the tool just to change a knurl. That would be very cumbersome and I am lazy.
I decided to add precision spacers adjacent to the knurls to maintain the arms at .380". These are just hollow tubes so they are easy to nail the tolerance required.
Here you can see one of the new spacers retained by a 10-32 screw.

1585880854833.png

This allows me to use a solid axle made from an old 1/4" drill.
You can see that I clearance drilled one side for the axle. The other arm has a hole that only goes half way through at full diameter. This will allow me to slide the axle in and hold it in place with a small cover plate. There is no significant lateral force on the axles. (I hope)
1585880988181.png

1585881001882.png

1585881015186.png

I just need to cut sections from that drill to act as axles. The cover plate with be elongated and held in place by the same #10 screw that holds the precision spacer. To change a knurl you simply loosen the #10 screw, slide the cover plate aside and slide out the axle.
I hope this it the final version but some testing is in order!

Robert
 

mattthemuppet2

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looks beautiful RWM and fantastic knurls too! If you want a way of retaining the axle, one thing I had planned to do with mine (when I build it!) is a small set screw intersecting the axle bore. You could even turn down the end of the set screw to make a pin. Then grind a notch in the axle to line it up with the setscrew. That way the axle can't move around but it should be straightforward to change knurls. Won't take up any space on either side of the side plates either.

I've also seen little swing down latches used, that clip into a circlip groove on the end of the axle. That would be even simpler to change knurls with..
 
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mikey

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Finally had a chance to go through this thread, Robert, and I should have read it earlier. I use a very quick and easy method to hold the pins in my knurler that I actually got from Guy Lautard's First Bedside Reader. I've been using this set up for over 20 years and my pins (drill blank) have no significant wear and the wheels can be changed out in a few seconds. You might consider it. See below:

pin1.jpg pin2.jpg

The pin hole in the arms is a through hole, reamed carefully for the 3/16" drill blank. Each pin has a 0.04" deep slot cut in one side with an abrasive wheel. A #6 stainless washer has a small flat ground on one edge that fits in the slot, and the washer is held in place by a 6-32 SHCS. This screw has never come loose, ever. To change wheels, just remove the screw and pull the pins. Takes just a few seconds to do.

I have a writeup on my knurler that I wrote over 15 years ago. I've been meaning to polish it up and post it but life has been hectic. This info is in that article so I should get off my butt and finish editing it. Sorry for being so late on this.

I noticed that your knurl in post 117 shows a tapering depth of pattern. That is probably due to the tensioning bolt loosening as you traverse down the knurl. Put a jam nut on it and lock it down before knurling and that should handle it.
 

rwm

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Matt- I though about doing it that way but I am terrified of 4-40 taps! I suppose I could go to #6.
Mikey- thanks for posting. That does look like a good idea. I have Guy's book. I will look back through it.
Robert
 
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Janderso

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Well that was fun.
Well done RWM. Beautiful work.
 
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mattthemuppet2

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Matt- I though about doing it that way but I am terrified of 4-40 taps! I suppose I could go to #6.
Mikey- thanks for posting. That does look like a good idea. I have Guy's book. I will look back through it.
Robert
ah, you'll be fine. 2-56 and 0-80 are where things get crazy :) A good spiral point tap will work wonders and you can always go up a drill size or two (say from 42 to 40) to reduce the cutting forces. It's not like high thread engagement is needed.

Mikey's version looks neat too. If you want to outfancy him, you could relive the washer on one side so you simply have to rotate it out of the way with the bolt loosened to remove the axle.
 

rwm

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...or for that matter use a plate that rotates into a slot pivoting on the #10 screw that is already there. Hmmmm.
 

Weldo

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How bout something like this. Pin with plate attached like they do for heavy equipment?

1585939950039.png
 

rwm

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I think I am finished!
I left one of the holes open in the first pic so you can see my solution.
1585960226270.png

1585960241324.png

It is now super easy to change out the knurls. If the axle sticks a little you can push it out from the other side.
I will update the prints soon.

Robert

EDIT: the only potential problem I can see is the axle rotating in the housing and wearing the arms. Mikey/Guy's solution would prevent that. I will have to keep an eye on this and see if I think that is happening.
R
 
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rwm

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Not finished! The doggone axles rotate during use. Not a lot but I suspect it will be a problem over time. I also looked at the write up in Guy Latard's book. Damn shame 'cause I like the way it looks! There are a couple of options here:

1. I can spot weld or TIG weld the tabs I made above to the ends of the axles. I could weld them "in situ" so the alignment will be perfect. (Weldo solution)
2. I can cut the tabs shorter and have them fit into slots in the axles. (Mikey solution)
3. I can cross drill the end of one arm and put a #6 set screw (or #8; which is less likely to break?) holding the axle on a flat. (Matt solution)

I believe all of these solutions will work. I am really torn about which route to take. #2 will involve new axles. #3 may be the most elegant. #1 is probably easiest but may look funky.
This has been an interesting journey although more complicated than I imagined. I really appreciate all the interest and suggestions along the way!
Robert
 
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DavidR8

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Finally had a chance to go through this thread, Robert, and I should have read it earlier. I use a very quick and easy method to hold the pins in my knurler that I actually got from Guy Lautard's First Bedside Reader.
I just went looking for that book. It’s over $200 on Amazon!


Sent from my iPhone using Tapatalk
 

mikey

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Yeah, it was much cheaper when Guy Lautard was alive and publishing.
 

mikey

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Not finished! The doggone axles rotate during use. Not a lot but I suspect it will be a problem over time. I also looked at the write up in Guy Latard's book. Damn shame 'cause I like the way it looks! There are a couple of options here:

1. I can spot weld or TIG weld the tabs I made above to the ends of the axles. I could weld them "in situ" so the alignment will be perfect. (Weldo solution)
2. I can cut the tabs shorter and have them fit into slots in the axles. (Mikey solution)
3. I can cross drill the end of one arm and put a #6 set screw (or #8; which is less likely to break?) holding the axle on a flat. (Matt solution)

I believe all of these solutions will work. I am really torn about which route to take. #2 will involve new axles. #3 may be the most elegant. #1 is probably easiest but may look funky.
This has been an interesting journey although more complicated than I imagined. I really appreciate all the interest and suggestions along the way!
Robert
#3 is how Eagle Rock does it. The advantage is that if you size it right you can use purchased carbide pins instead of making them. All you would need to do is put the set screw in the right place. You might call Eagle Rock for the dimensions of their pins or ask @darkzero to measure his for you.

#2 just works. However, it restricts you to making and using your own pins.

If this was me, I would go buy the pins.
 

darkzero

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I purchased my carbide pins from Accu-Trak. They're available in a number of common sizes. Fit my knurler perfect. They can also make custom sizes.

 

mikey

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I purchased my carbide pins from Accu-Trak. They're available in a number of common sizes. Fit my knurler perfect. They can also make custom sizes.

Thanks, Will.

So, no flats on the pins. Just need a set screw in each arm and you're done, Robert. I do hope you reamed the hole for the pins carefully.
 

darkzero

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My pins don't have flats on them, set screws hold them fine. Since they're harder than the set screw no worry of raising a burr. The pins that came in my knurler didn't have flats on them either, they were carbide too but they weren't original. Doesn't need much force from the set screws to keep em in place.

I'm not sure if the K1-44 originally comes with steel or carbide pins & I'm not sure if steel pins have flats on them if it does come with steel pins. For most scissor knurlers the pins are pressed in so maybe steel pins from Accu-Trak don't normally come with flats.
 

mikey

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The K1-44 comes with steel pins that have no flats on them. Mine have no burrs from the set screws so I'm sure they're pretty hard, although I haven't taken my Tsubosan files to them.
 

rwm

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I did not ream the 1/4" holes (embarrassed.) They are not too sloppy though. I suppose slight wobbling of the axle could cause set screw loosening over time. What is the geometry of the Eagle Rock knurler? i.e. where is the set screw in relationship to the angle of pressure on the axle? I was thinking of putting the set screw on the front so the axle is pushed at an angle 90 deg from the axis of the screw? I may experiment (on scrap) as see if I can get a #10 set screw in the 1/4" arm plate.
Robert
 

mikey

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The set screws are on the top of the upper arm and bottom of lower arm. Pretty sure they're #8 set screws.

Yeah, if the pin bore is not accurate the pin can move/vibrate and may cause the set screw to loosen. On the other hand, it might still work so it's worth a try.
 
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rwm

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I was also considering using the set screw on the far side to make the hole non-round. I could loctite it in place, have a flat on the end of the axle and keep my plates to retain the axles. Just a thought.
R
 

mikey

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I was also considering using the set screw on the far side to make the hole non-round. I could loctite it in place, have a flat on the end of the axle and keep my plates to retain the axles. Just a thought.
R
I don't understand about the non-round hole, Robert.
 

rwm

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The set screw would not have to be tight on the axle to prevent rotation. It could just engage the flat to prevent it. Kind of like using a semicircular hole and have the end of the axle as a semicircle. Probably unnecessarily complex and I should just have the set screw both retain the axle and prevent rotation. Another though was to drive a roll pin across the hole and slot the end of the axle. Just brainstorming here.
R
 
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mikey

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The pin just needs to stay in place. How you do that is up to you but the simpler, the better. A set screw would be simplest. I chose Lautard's method because I didn't have enough real estate for a set screw. Mine accomplishes the same thing as a set screw, just more hassle to make.

The concern with a set screw is the accuracy of the pin hole, which is why I asked if you reamed it carefully. If the pin moves around a lot then that set screw might not hold it. The only way to know is to try it and see, and if it was me I would try the set screw and see if it suffices. If it does then you have the option of using carbide pins and that is a very good thing.
 
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rwm

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How's this?!

1586044413482.png

1586044472994.png

After experimenting, I actually got #10 screws in there. I think there is enough "meat" to hold them. I placed the set screws so they are accessible from the front and the knurl wheels push perpendicular to their axis.

Robert
 

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mikey

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turnitupper

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This allows me to use a solid axle made from an old 1/4" drill.
If this has not already been mentioned drill shanks are neither HSS nor hardened to any degree to allow gripping of the chuck.
I have some cheap solid carbide end mills that spark the same on the shank as near the cutting edge with a grinder, maybe an alternative if you envisage heavy usage.
Brilliant build so far, looking forward to versions 2 to10. :applause:
John.
 

rwm

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Thanks for the compliment T- I thought about that earlier. One of the axles is from a double ended center drill which seems to be hardened in its entirety. The other is a cobalt drill shank. It was very hard to cut with an abrasive blade so I don't know. Certainly harder than mild steel. I will try to trash a carbide end mill very soon to resolve this issue!
Robert

Edit: I could harded the axle, yes? Use the process for O1?
Robert
 
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