Knurling tool build

Cadillac STS

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One knurling project could be making a nice 2 inch or so knob to fit the tightening bolt. Would be nice to be able to tighten it with no tool.

Countersink the bolt head into the knob, thread it and put another nut against it to hold it in place.
 

rwm

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I already thought about that! Thanks!
Robert
 

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My toy mill is not going to be able to cut that slot. Hence plan B. Plus that is a lot of steel to subtract.
I just made a test joint using nickel silver. It flows at a much lower temp and made a very solid joint. That may be the way to go. My brazing rod is coated with blue flux. Is there a specific flux I could/should pifut inside the joint in addition?
Robert
Not sure if anyone chimed in but powdered borax is the about the best for brass . You dont need high price named borax. And i think your design will work great as a two jaw knurl.
 
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I used this setup to drill and bore the larger holes:

View attachment 316922

I decided to reduce the threaded pivot hole to 5/8". That should be plenty large. I had about 1/8" clearance on the swing.

Here's where we are.

View attachment 316924

You may notice I used DTMS welding on the wings. This causes a lot less distortion than TIG.

I have a plan to propose; back to the axles: One issue is the arm spacing needs to be fairly accurate for the knurl wheels to run properly. The wheels are 0.375 wide. I would like the arm spacing to be about 0.378. The only way I can see to effectively accomplish this it to use an axle with a shoulder that abuts the arms. My plan is to use a hollow axle. It would be 0.250 diameter and 0.378 wide. It would be drilled to accept a #8 screw and clamped in place by that screw between the arms. I would like to use a #10 but that would leave the wall thickness of the axle at about 0.030" which I don't feel good about. I don't see a #8 screw shearing under this load? I could use O1 tool steel if people think a hardened axle is important? I could also make spare axles easily. I am open to other suggestions.

I am excited to grind the tabs off the arms and separate the two pieces!

Robert
Ever thought of dowel pins there hardened and should hold up. Just a thought
 

rwm

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Detail of upper pivot. The screw is turned down to 3/16" and there is a C clip retaining it.
1584904652122.png
Mounted:
1584904745843.png

1584904758959.png

First aluminum:
1584904783355.png

Then 304 SS:
1584904843433.png
You can see, one did not work so well. One of the wheels double tracked?

Robert
 
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Weldo

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The first set is beautiful! Isn't it true that there is one perfect diameter for a given pitch of the knurl wheels? Maybe on the second set the work was not the correct diameter?
 

rwm

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The first set is beautiful! Isn't it true that there is one perfect diameter for a given pitch of the knurl wheels? Maybe on the second set the work was not the correct diameter?
Correct (sort of.) There are multiple diameters that a wheel can run perfectly based on the knurl pitch. But not all diameters. It can be calculated but trial and error works too. I used two different pitches on the SS. Only one worked correctly.
I am thinking the best way to do this would be to mount the tool on the back side of the cross slide on a rigid mount. Then you could see the action better and the tool would be more rigid than in the QCTP.
Robert
 
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Weldo

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I see.

Mounting to the backside sounds like a nice idea, for viewing purposes.
 

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Do you think the steel one just needed more pressure to make the points form up?
 

Weldo

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Stainless steel will work harden if I'm not mistaken. That may make a forming operation like knurling to be very difficult to get good results maybe. Or maybe it could be annealed before knurling?
 
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rgray

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I am thinking the best way to do this would be to mount the tool on the back side of the cross slide on a rigid mount. Then you could see the action better and the tool would be more rigid than in the QCTP.
Funny you should mention that.
Here's a pic of the only knurler I left out of the earlier picture.

20200322_155116.jpg
 
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Lo-Fi

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See if there's anything in there that helps with the double tracking. I've never tried stainless, but I'd expect it to be tricky!

Lovely build :)
 

rwm

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I added the prints to the first post of the thread so they would be easy to find. Let me know if you see any errors. There are some slight variations in my execution but enough information is there.

Robert
 

rwm

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That video from Joe P is kind of funny. He goes through the calculations for ideal diameter and TPI. Then he goes over to the lathe and demonstrates that it doesn't work! Still a great video as all of his are.
Robert
 

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I added the prints to the first post of the thread so they would be easy to find. Let me know if you see any errors. There are some slight variations in my execution but enough information is there.

Robert
I thought the design would work well. The stronger thicker arms n body. Have made this a real all day worker for you. Id download the prints but ah its the hospital life for me for a while longer. Thanks for distracting me from pain n where im stuck.
 

rwm

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I made the rear mounted holder. Just used beefy aluminum:

1585354347224.png

1585354362485.png

Thanks Russ! It is much easier to check the pattern and follow the result.

I used the O1 hollow axles and put #8 alloy machine screws through them. So far so good. With this design I think this type of axle is important to maintain the arm spacing for the wheels. The Hardened O1 is significantly harder than a grade 8 bolt. I made an update to the prints to reflect this important point.

Robert
 
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rwm

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Interesting idea! I can't easily do that because the hole in the upper wing is only 3/8" diameter and there is not much room to go larger. The screw is 3/8-16 so....
R
 
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Cadillac STS

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Then you can see what you are doing as you tighten it with it running
 

Cadillac STS

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Interesting idea! I can't easily do that because the hole in the upper wing is only 3/8" diameter and there is not much room to go larger. The screw is 3/8-16 so....
R
1/4 20 bolt and re do the brass nut?
 

rwm

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1/4" might be kind of flimsy when extended. There is actually a lot of clearance on the back side so it is not hard to adjust. Maybe if someone else builds one of these they should try the reverse screw idea. You could use a larger pivot on the top wing and make it work.
Robert
 

rgray

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Consider switching the tightening screw around so you can adjust it from the front.
At large dia it looks like it may run into interference with the top wheel? Maybe not, just spitballin.

Thanks Russ! It is much easier to check the pattern and follow the result.
Looking good. Looks like it will be a pleasure to use.
One thing I tend to do with mine is adjust it down to the work, then move it off the work and adjust it tighter. Then I can either
force it to center on the work once it's turning or just bring it far enough on it till getting the result I want.
Works for stock that's large enough to take some side load. Small work will of course bend away.
It doesn't create as much side load as a push knurler so works good.
 

rwm

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I tried a long segment of 1/2" 304 SS today:

1585503597406.png

The forces when doing this were very high. The tool was actually pretty warm when I stopped. I did not expect that. The far end is held by a live center so it wouldn't deflect. I used power feed away from the chuck. You can see that the knurl is more fully formed at the beginning since the tool dwelled here due to clutch slipping. The far end is incompletely formed but still looks nice. It's not perfect but I would call this usable. I can machine this into thumb screws. Stainless is much harder to knurl than aluminum!
Could I go back and machine off the tops of the diamonds with a skim cut to make it look more even? Don't want to mess it up.

Robert
 

rwm

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I did this:

1585617669996.png

I have to confess; I tried to do a press fit and got a barely interference fit. It is tight but not solid. I put some red Loctite in there. I will destruction test it tomorrow. If it fails, then plan B.
There is a hole bored in the back of the handle so you can also use an Allen key also. You would never get this tight enough by hand.
(No, I did not do that knurling. I got the handle super cheap on eBay.)

Robert
 

rgray

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Looking good. That will be a joy to use.
 

rwm

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1585665708848.png

I think I am going to remake the center bushing to accommodate a 5/16" screw. Future project may be to still revise the axle design.

Robert
 
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