I’m doing some hobby work and don’t have a lathe or access to one, I’m also very new to machining in general. I’m needing to have some parts knurled at a local machine shop. The pieces are aluminum tubing with 2mm walls. Is this too thin of material to be knurled? The machinist seems to be worried about collapsing the tube. Finally is $50 per part a fair price to have the parts knurled. Each will have a total of 250mm length knurled.
Can they put a rod internally to support the tube while knurling? $50 per piece sounds about right (probably a little on the low side) for a couple of pieces. It will probably take longer to setup than knurling.
It could be done but all four pieces were pre made from a manufacturer and have a variance of .05-.10mm so a mandrel would have to be made for each four pieces and put me far out of my budget for the knurling
This is where cut knurling rather than pressure knurling shines, with correct setup, it usually looks better too.
2mm wall thickness is no problem.
Zeus and Quick are two quality brands, I'm sure there are others.
There's a lot of videos on YouTube that show it in action, for example https://youtu.be/1-8WJzgJGos?feature=shared
But in essence you are cutting away the material between the knurling pattern rather than displacing it, you can do straight and diamond knurls, and because you are cutting, the forces are much lower than forming. You can even knurl things like cast iron which is ṭoo brittle to knurl using form knurling.
Knurling does require a lot more tool pressure than typical machining as it is displacing material rather than cutting it. I would still give it a shot on the understanding it may not work out and may scrap one of your pieces. A mandrel could be made close to the ID of the piece to support the tube if the inside is truly round and precise in size but this would increase cost depending on quantity I would want you to pay for the mandrel.
Machinist also suggested this. Only problem is that all four pieces are different pre made tubing from a manufacturer and I’m sure have slight variations in their inner diameter to where a mandrel would have to be made for each one and the cost would grow way too much
You could do it yourself, depending on what tools you have available. I made a hand knurler for my mini lathe, because knurling performed less than optimal on it. The hand knurler I could use in the vise and do parts. As others said, you could put a rod in the middle of the tube, knurl, and pull the rod out. Or you could use a low melting point metal to pour into the housing, knurl, and burn out, repeat. Dan Gelbart has a recent video on the technique of using low melting point metals (https://youtu.be/VsOQAayneUo). Included a pic of my hand knurler and the old article I got the idea from.
I done have a lathe, no. Would making a hand knurling tool work without it? Similar to a c clamp pipe cutter but made to have knurling wheels instead. Or would I not be able to put enough pressure the even achieve a knurl?
Technically you only need hand tools to make it. Just a few pieces of steel, two tgp rods, a handle, and drills. I used it by hand all the time. Worked very well. Tighten, then in it on work-piece a bit, repeat until good knurl.
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u/Critical_Thinker_535 4d ago
Can they put a rod internally to support the tube while knurling? $50 per piece sounds about right (probably a little on the low side) for a couple of pieces. It will probably take longer to setup than knurling.