View Full Version : I may need a custom screw machined
Dubis7 05-26-2017, 09:53 PM So I was working on my Norelco Continental 300 tape recorder today, took out a screw that holds the oil wick for the bottom flywheel bearing, and the darn thing snapped in half when I was screwing it back in. Near as I can tell, it's pot metal that weakened over time. It's not a hugely complicated part, and I'm attempting to JB weld it back together considering it was a fairly clean break, but if that fails I need to replace it. This is kind of an oddball piece; the thread itself should be standard, but it's more of a hollow cylinder with a single flathead hole on the bottom.
Does anyone have access to or can recommend someone to custom machine a new part? This has been a long restoration job, and I'd hate to lose it to an unobtanium part right at the end.
Chip Chester 05-26-2017, 10:06 PM A hollow cylinder with a single flathead hole on the bottom.
A single hole for a flathead screw, maybe? As in, countersunk? A pic or drawing would really help here. Plus an idea of whether you think it can be made by modifying an existing item, like a threaded bushing.
Chip
Dubis7 05-26-2017, 10:14 PM I'll get pics tomorrow, once the JB weld is done and I've tested it.
If it helps, it's a hollow core, one end open, the other end closed with a sunken flathead grip. I think I could possibly modify an existing metric screw to do what I need, but I'm a hair concerned about trying to hollow one out to hold the material.
Dubis7 05-27-2017, 04:14 PM My repair failed. I'm at a loss. I went out and got some screws that match, so I can at least get a part in there, but I'm not sure what to do about the little black plastic (?) cap. Does anyone have a source for a machine shop or someone who can take my part and repair/replicate it?
Jon A. 05-27-2017, 05:41 PM That doesn't surprise me, I've used that sort of thing before without success.
Anyway, that looks easy enough to duplicate, it isn't a far cry from an ordinary set screw. I would use a couple of nuts at the top to help lock one into position in a vise, cut it to size and file the threads off the end, then just use a drill press (if I had one) to drill the hole I want. I'd measure the drill bit first and put tape on it in lieu of a depth gauge.
Notimetolooz 05-27-2017, 07:08 PM I do some machining. I've got a lathe. You could either take several measurements, like thread and length, etc. or send it to me to duplicate. Probably wouldn't cost much more than the postage. I'd start out with a commercial bolt if I could just to avoid cutting the threads.
Dubis7 05-27-2017, 08:56 PM Ok, so, I may have found a solution to this. If I'm wrong, I'd like to pursue getting the part machined.
Turns out this actually is a standard part, it's just not that common. It's called an extended tip set screw.
https://www.mcmaster.com/#set-screws/=17td1yk
I've ordered some (box of 100 for 6 dollars, so let's hope I'm right) and at least know the threading and diameter will be correct.
Right now my only concern is that the tip on the broken part is a sort of black plastic, while the newer one appears to be all steel. Maybe that's just a matter of improved design, but I suppose I'll find out.
Anyway, thanks for the help. I'll update once the part comes in, and will potentially reach out for help should I need the replication. I still have the broken piece, so I'll be able to keep it as an example.
dtvmcdonald 05-29-2017, 08:41 PM Also look at the nylon-tipped stainless steel set screws. They are
wonderful things, I used hundreds in my work holding in expensive
laser mirrors. I never chipped one!
Dubis7 06-02-2017, 07:47 PM Well, lucky me, the new screws worked.
Here's my now repaired Norelco Continental 300 next to my next project, a 1960s GE Toast R Oven
Thanks to everyone that helped me out!
|
|