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Knurling thread by George Wilson...
- Thread starter Nelson
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What do you need elaborated on? I wrote a pretty comprehensive write up on the process,but will be happy to answer other questions. A few guys have use this info to make their own knurls.
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- Sep 22, 2010
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George,
Thanks for responding, I need you to back up a bit, how do you FIRST set up your lathe for the process of knurling- the blank, the tool, get everything positioned properly before you even start doing anything?
Thanks!
+#$
Nelson
Thanks for responding, I need you to back up a bit, how do you FIRST set up your lathe for the process of knurling- the blank, the tool, get everything positioned properly before you even start doing anything?
Thanks!
+#$
Nelson
- Joined
- Jul 26, 2011
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- 4,139
As shown in one of the pictures,I turn the blank out of a piece of 01 drill rod. I was holding the 3/4" drill rod in a collet,but it can be held in a regular chuck.
A hole for the axle of the knurling tool is first drilled with the tailstock chuck after it is center drilled.
The lathe is best run slowly when cutting tool steel. The Hardinge HLVH's lowest speed is 135 RPM,and that is what I used to prepare the blank,and to hob the teeth onto the knurl.
The reason I use 01 drill rod,is because W1 cracks so easily in hardening,due to the rapid shock of water quenching. 01 is also a more durable steel,and knurls do suffer a lot of stress in use.
The most important thing is to get the contour of the knurl as close to the same diameter as the tap as possible. If you don't get the knurl close,problems with messy hobbing of the blank will develop,and the knurl will likely get ruined.
When using the knurl after it is made,the surface of what you are knurling must also closely match the knurl's concavity. If not,the metal being knurled will become too mangled during the knurling,and will start flaking apart,or becoming work hardened,and the knurl will get ruined. What the object is,is to deform the metal being knurled as little as possible. Brass will start to flake and fall apart,and steel will become work hardened,and ruin the knurling wheel.
A hole for the axle of the knurling tool is first drilled with the tailstock chuck after it is center drilled.
The lathe is best run slowly when cutting tool steel. The Hardinge HLVH's lowest speed is 135 RPM,and that is what I used to prepare the blank,and to hob the teeth onto the knurl.
The reason I use 01 drill rod,is because W1 cracks so easily in hardening,due to the rapid shock of water quenching. 01 is also a more durable steel,and knurls do suffer a lot of stress in use.
The most important thing is to get the contour of the knurl as close to the same diameter as the tap as possible. If you don't get the knurl close,problems with messy hobbing of the blank will develop,and the knurl will likely get ruined.
When using the knurl after it is made,the surface of what you are knurling must also closely match the knurl's concavity. If not,the metal being knurled will become too mangled during the knurling,and will start flaking apart,or becoming work hardened,and the knurl will get ruined. What the object is,is to deform the metal being knurled as little as possible. Brass will start to flake and fall apart,and steel will become work hardened,and ruin the knurling wheel.
I have a clamp style knurler that I made (my current avitar). I used knurl wheels I purchased from LMS. I also have a simple single wheel bump knurl tool that does a straight knurl. My question pertaining to this thread, can I use the single straight knurl wheel paired with a smooth wheel in the clamp knurl tool? Could I use the single straight knurl wheel to duplicate itself from O-1? Or do I need to just buy a pair of sraight knurl wheels?
Chuck in E. TN
Chuck in E. TN
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If I understand you,you are running a clamp type knurling tool holder with 1 straight knurl wheel,and 1 blank wheel. If that is correct,definitely take the straight knurl wheel and make another straight knurl wheel with it. The blank wheel running opposite your blank wheel is a huge no-no.
I don't know the maker of your existing plain knurl wheel. Before you try knurling annealed 01 drill rod,take the wheel out and try running a SMOOTH CUT,new Nicholson file against the SIDE of the wheel,to make sure it is HARDENED. You could just make a simple,1 wheel knurling tool holder like I used in my pictures,and just do the knurling with 1 wheel,unless you have a very light lathe,and are worried about the amount of pressure that single wheel knurling will put on your spindle bearings.
I'll mention that for brass,a FINE pattern knurl,rather than a coarse pattern knurl works better,as less brass is displaced and squeezed into a smaller pattern. You don't want the brass to start to flake off from being over worked. When that happens,you'll never get a clean knurl. I haven't tried annealing cold rolled brass stock before knurling,but I'll bet it would help to get a good coarser knurl because the brass hasn't already been partially work hardened by the cold rolling process (hence the name "half hard,or full hard brass").
To anneal the brass,heat it to dull red,and just let it cool in the air. Be advised though,when you take the temper out of brass,it reverts to the strength of cast brass. If you are knurling a smallish SCREW,best leave it hard,and use a fine pattern knurl. Cast brass screws easily wring off. If it is just a knob you are making,it won't matter.
In the 18t.C.,you will always see brass hinges with iron screws in them on wooden boxes. They only had cast brass,and knew it was weak. Someone in Holland figured out how to make stronger brass pistol barrels,for use around salt water,by rolling brass sheet around a mandrel,silver soldering it,then HAMMERING the brass all around. He was making cold rolled brass out of the weaker cast brass. Naval pistols frequently had cast brass barrels at the time. At Mt. Vernon,you can see Washington's brass barrel pistols. One is burst open. It did not have a hammered brass barrel.
I don't know the maker of your existing plain knurl wheel. Before you try knurling annealed 01 drill rod,take the wheel out and try running a SMOOTH CUT,new Nicholson file against the SIDE of the wheel,to make sure it is HARDENED. You could just make a simple,1 wheel knurling tool holder like I used in my pictures,and just do the knurling with 1 wheel,unless you have a very light lathe,and are worried about the amount of pressure that single wheel knurling will put on your spindle bearings.
I'll mention that for brass,a FINE pattern knurl,rather than a coarse pattern knurl works better,as less brass is displaced and squeezed into a smaller pattern. You don't want the brass to start to flake off from being over worked. When that happens,you'll never get a clean knurl. I haven't tried annealing cold rolled brass stock before knurling,but I'll bet it would help to get a good coarser knurl because the brass hasn't already been partially work hardened by the cold rolling process (hence the name "half hard,or full hard brass").
To anneal the brass,heat it to dull red,and just let it cool in the air. Be advised though,when you take the temper out of brass,it reverts to the strength of cast brass. If you are knurling a smallish SCREW,best leave it hard,and use a fine pattern knurl. Cast brass screws easily wring off. If it is just a knob you are making,it won't matter.
In the 18t.C.,you will always see brass hinges with iron screws in them on wooden boxes. They only had cast brass,and knew it was weak. Someone in Holland figured out how to make stronger brass pistol barrels,for use around salt water,by rolling brass sheet around a mandrel,silver soldering it,then HAMMERING the brass all around. He was making cold rolled brass out of the weaker cast brass. Naval pistols frequently had cast brass barrels at the time. At Mt. Vernon,you can see Washington's brass barrel pistols. One is burst open. It did not have a hammered brass barrel.
I just clicked spell check on my post and it disappeared!
George, thanks for the input. I'll get some O-1 in the correct diameter and try making one.
DaveH, I made a rubber blank wheel from a slice of 1.270" hard rubber roller from a printer.
I drilled the steel center to fit the knurler axel, mounted it on a bolt as a mandrel and turned the rubber to just a bit bigger than the dia. of the single knurl wheel.
A test run, on a piece of scrap shows it will work. The scrap was a rough piece of 6061 alu. Compression of the rubber was enough to allow the arms of the knurler to contact the work. I'll make another on about 1/4" bigger and try it.
Shows promise!
Chuck in E. TN
George, thanks for the input. I'll get some O-1 in the correct diameter and try making one.
DaveH, I made a rubber blank wheel from a slice of 1.270" hard rubber roller from a printer.
I drilled the steel center to fit the knurler axel, mounted it on a bolt as a mandrel and turned the rubber to just a bit bigger than the dia. of the single knurl wheel.
A test run, on a piece of scrap shows it will work. The scrap was a rough piece of 6061 alu. Compression of the rubber was enough to allow the arms of the knurler to contact the work. I'll make another on about 1/4" bigger and try it.
Shows promise!
Chuck in E. TN
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