Slimy38
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| posted on 9/1/21 at 09:45 PM |
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Grub screws in damper collars
My adjustable suspension has the aluminium collars for the spring seats, these lock in place with an M6 grub screw. Problem is the grub screw has
turned to mush over time. I got it all separated and removed the offending screw, but the replacement ones I bought don't have the correct
thread pitch. It's finer on the new screws than it is on the old.
What's the best way of identifying the thread, and what options will there be? Normally I'd measure ten peaks and divide by ten, but these
only have maybe three or four so I'm wary that I can't measure it that accurately.
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gremlin1234
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| posted on 9/1/21 at 10:16 PM |
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the engineering way is to use a thread gauge,
however, if you take another bolt, and match the threads back-to-back ie hold the threads together with heads at opposing ends, then it should be easy
to match.
(but this won't help on mail order parts ;-(
but perhaps you could match it with another longer bolt, then count its tpi.
else give us a photo, and we may recognise it!
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harmchar
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| posted on 10/1/21 at 12:04 AM |
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A thread chaser repair kit like the attachment is invaluable when fixing up cars n stuff in the workshop. I have the Snap On version of this and
it's brilliant.
https://ebay.us/EXDGnE
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coyoteboy
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| posted on 10/1/21 at 07:08 AM |
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https://www.amazon.co.uk/dp/B071H8GP18/ref=cm_sw_r_cp_apa_i_2EQ-FbHXTN7
3Q
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westf27
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| posted on 10/1/21 at 09:50 AM |
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Just drill and tap another hole ?
555
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Slimy38
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| posted on 10/1/21 at 10:45 AM |
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quote:
Originally posted by westf27
Just drill and tap another hole ?
That had occurred to me, I was even wondering whether retapping the existing hole would be sufficient. The collar is aluminium so it wouldn't be
a difficult job. I'll see if I can get a guide on the proper thread size and whether I can get the screws at a decent price, then look at a new
hole if I have no luck.
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Slimy38
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| posted on 10/1/21 at 10:48 AM |
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quote:
Originally posted by gremlin1234
but perhaps you could match it with another longer bolt, then count its tpi.
Doh! Yep, that would be an easier way of getting an accurate measurement! I'll see what I can find as a match.
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Slimy38
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| posted on 10/1/21 at 12:28 PM |
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The plot thickens... so the thread matches to an M8 bolt that I had to hand, which according to the book is a 1.25mm pitch. I measured the same as
best I could and it is indeed a 1.25mm pitch.
M6 x 1.25 does show up for some fixings (mainly furniture for some reason?) and I can even find taps for that size, but no sign of grub screws. 1mm
pitch seems to be the standard one.
So now I'm wondering whether it's an imperial thread. The closest I can find is a 1/4 inch with 18TPI, but that also seems to be an
unusual thread.
Has anyone got any suggestions before I dig out my M6 x 1 tap and just cut a new hole?
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JMW
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| posted on 10/1/21 at 12:38 PM |
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1/4 inch unc, or whitworth for that matter, is 20 tpi (or 1.27mm pitch).
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Slimy38
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| posted on 10/1/21 at 12:46 PM |
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quote:
Originally posted by JMW
1/4 inch unc, or whitworth for that matter, is 20 tpi (or 1.27mm pitch).
Sounds good, I managed to find them for a couple of quid so I've ordered some. Thanks for the information.
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coyoteboy
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| posted on 10/1/21 at 02:19 PM |
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Ignore me, I misread your m6 lol
[Edited on 10/1/21 by coyoteboy]
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gremlin1234
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| posted on 10/1/21 at 03:37 PM |
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quote:
Originally posted by Slimy38
quote:
Originally posted by JMW
1/4 inch unc, or whitworth for that matter, is 20 tpi (or 1.27mm pitch).
Sounds good, I managed to find them for a couple of quid so I've ordered some. Thanks for the information.
1/4 whit. is the standard 'tripod' thread for small cameras. so they may give you something to gauge it against.
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Slimy38
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| posted on 10/1/21 at 05:05 PM |
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quote:
Originally posted by gremlin1234
1/4 whit. is the standard 'tripod' thread for small cameras. so they may give you something to gauge it against.
I just so happen to have a small desktop tripod, and yes, it screwed in perfectly! Thanks for the suggestion, that confirms I have the right ones on
the way.
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