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Mike Burch
01-23-2018, 03:53 AM
I have a need to pin a thermostatic switch to the outside of the motor case on my lathe so that next time it overheats it turns off before letting out the start capacitor's magic smoke.
I'd like to use a couple of those tiny little rivetty things that are used to pin name plates, etc, to castings.
But I can't find them illustrated on the websites of any of my local fastening suppliers, and I don't know what they are properly called anyway, so I can't do a sensible search.
Can anyone help with the right name, please?

The Artful Bodger
01-23-2018, 04:00 AM
Hi Mike, I have never been able to find those little rivet like things but I have used tiny screws salvaged from old camera lenses in their stead.

I have only heard the name as 'name plate rivets'.

Cheers from Ashburton.

IanPendle
01-23-2018, 04:16 AM
Try 'drive pins'.

DOH! edited - of course they are 'drive screws' as per the following posts!

Ian.

Magicniner
01-23-2018, 04:36 AM
Drive Screws?

http://catalog.scfastening.com/viewitems/screws-drive-screws/drive-screws?

bjmh46
01-23-2018, 05:16 AM
Sometimes referred to as "PK drive screws". Parker-Kalon is/was the manufacturer.

old mart
01-23-2018, 08:10 AM
Why not a thermal adhesive?

CCWKen
01-23-2018, 08:41 AM
Why not use just plain screws? If you ever have to replace the sensor, you'll have to disassemble the motor to punch the drive screws out from the inside. Assuming you drilled through to start. One of my pet-peeves, for restorations, is companies (or people) that install data plates using drive screws without a through-hole. :)

As a side note: You can sometimes remove the drive screws with a V-notched tool. Sometimes, they have to be drilled out. :cool:

gzig5
01-23-2018, 10:25 AM
Pop rivets.....

RichR
01-23-2018, 10:32 AM
It's a serviceable part. Mount it in a way that it's serviceable without drilling or ripping the motor apart.

Mike Burch
01-24-2018, 02:08 AM
Thanks for the help and the suggestions, gentlemen.

Old Mart, I did try thermal adhesive, but was too impatient, I guess, and it let go when I put pressure on it. I cleaned everything up and tried again, and this time left it overnight. And behold! it was solid. So that's what I'll stick with (pun intended!).

Thanks again.

Forrest Addy
01-24-2018, 02:25 AM
Open the motor and bond that "snap action" thermostatic switch direct to the stator iron, wherever there's a place to mount it so the face is solidly coupled to the mass. Mount it on the outside and the device is exposed to ambient air.

old mart
01-24-2018, 03:53 AM
It would be a good idea to check the glue occasionally, its not fail safe.
The museums drill mill has a 1.5 hp single phase motor, and one of the volunteers made an improved cowling to make the fan more affective, it runs noticeably cooler now.

Mike Burch
01-24-2018, 05:57 PM
Thanks for all the suggestions.

Forrest Addy, opening this replacement motor would void the warranty, and anyway, the likelihood of my finding a flat surface in there is remote. But the theory is good, so thanks for the thought!

The problem is that the alleged one horsepower motor is only the same size as a normal half-horse motor, and furthermore has no cooling fins on the case! The lathe is new, and the motor failed well within the warranty period, and has been replaced with the new one.

Unfortunately the space allotted by the lathe manufacturer is too small to allow the fitting of a real one-horse motor. So rather than replace the motor with a layshaft which would be driven in its turn by a decent motor slung off the back of the bench (possibly a 3-phase driven by a 1-to-3-phase VFD, like my mill) I have taken a much cheaper route, which I hope will prevent a repeat of the problem.

I have fitted a computer-type fan with its 3 cubic metre (106 cu ft) per minute exhaust ducted to the rear of the motor, and in addition have fitted the thermostatic switch to kill the current if the case temperature gets above 60 Celsius (140F).

It's only fair to add that the vendors of the lathe have been prompt and argument-free in replacing the motor. Pics and specs can be seen here:
https://www.machineryhouse.co.nz/L149