hazmat74
Member
I'm probably going to turn a couple of sets of these this weekend. My question is, when drilling them for use on a mandrel, what size drill should I use? I'm assuming a 7mm will be a tad too large.
Question about delrin bushings
- Thread starter hazmat74
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walshjp17
Member
If I recall correctly, most mandrels are either 7mm or 8mm. You'll need to adjust your drilled holes accordingly. If you use any of the Berea kits that have bushings IDs ending in a B (e.g., 19B) you'll need the 8mm mandrel. I believe everyone else sells 7mm mandrels.
Why drill them for a mandrel? Put a 60* cone in each end with a hole starter bit and lose the mandrel. If you insist on using one...get out your calipers, measure the shaft diameter and go to the conversion guide in the library to find the drill size.
hazmat74
Member
Don't have the proper centers just yet, but this is what I will do when I have them. I have yards of delrin on-hand. Thanks for the suggestion.
arioux
Member
7 mm is the outside diameter of the tube. I think the madrel itself has 1/4 inch
RetiredJake
Member
The 7 mm mandrel is a letter "D" drill size, 0.246"
Jake
Jake
Dan Masshardt
Member
Matt - what kits are you making them for?
edstreet
Member
Become one with the caliper.
"D" drill bit I use this bit to make my bushings.
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hazmat74
Member
Just slimlines at the moment. That's all I have. I probably don't really need them, but I feel like playing with my metal lathe while I await a shipment from PSI.
Dan Masshardt
Member
Might not be a bad idea to turn some cone shaped delrin bushings for finishing too. You can use them for any size tube. I use them and they work well for me.
That way you can use them with new kits and then turn the right size later if you decide it's a kit you're going to use regularly.