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Old 08-17-2004, 08:38 AM   #1
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Default Head screw stripped, Helicoil?

head screw stripped, can i use a helicoil? i found a 4-40 but no metric ones. this would work but i would, of course go ahead and do all 4 of them. would this be strong enough?
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Old 08-17-2004, 08:48 AM   #2
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Default Re: Head screw stripped, Helicoil?

Quote:
Originally posted by GrandeGixxer
i found a 4-40 but no metric ones.
mcmaster has it. part # 91732A773 (18-8 SS Standard Helical Insert M3-.50 Internal Thread, 6.0mm Length)

i re-tapped mine with #6-32 and it seems to work ok (need to enlarge the hole on the button head for the #6 screw to go through)
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Old 08-17-2004, 03:09 PM   #3
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will that take the original bolt or will i need to replace them? i dont know the pitch for the stock ones.
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Old 08-18-2004, 08:09 AM   #4
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Quote:
Originally posted by GrandeGixxer
will that take the original bolt or will i need to replace them? i dont know the pitch for the stock ones.
need to replace the original screw with a #6-32 screw. the stock cooling head screws are M3X0.5. a #6 screw is about 3.5mm in diameter.
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Old 08-18-2004, 09:21 AM   #5
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18-8 SS Standard Helical Insert M3-.50 Internal Thread, 6.0mm Length

Metric 316 SS Socket Head Cap Screw M3 Thread, 10mm Length, .5mm Pitch, Packs of 50

http://65.54.184.250/cgi-bin/linkrd?...pagenum%3d2934

http://65.54.184.250/cgi-bin/linkrd?...pagenum%3d3059

that is what i ordered
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Old 08-18-2004, 10:05 PM   #6
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DATA, mcmaster is really fast. i ordered the stuff last night and it was here today.
unfortunatly, the helicoils are too big in diameter for the 3 mm bolts. i dont know if they packed the wrong ones or if they shrink, or if they take a larger bolt. the ones i ordered i thought were supposed to taka an m3 x .50 screw but it is way loose in it. it is closer to like a 5-40 size helicoil. aargh. very frusterating. what should i do? by the way, i am trying to fix an ns3 i got from a buddy in exchange for my starterbox that i loaned him and got stolen from the fuel nats in san jose. if anyone was there and knows anything about somone ending up with a nice new xtm starter box, let me know. i would like to get it back if it was left there on accident
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Old 08-19-2004, 12:04 AM   #7
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Quote:
Originally posted by GrandeGixxer
unfortunatly, the helicoils are too big in diameter for the 3 mm bolts. i dont know if they packed the wrong ones or if they shrink, or if they take a larger bolt. the ones i ordered i thought were supposed to taka an m3 x .50 screw but it is way loose in it. it is closer to like a 5-40 size helicoil. aargh. very frusterating. what should i do?
if you could turn a M3 screw into the coil for more than 3 to 4 turns then it should be the correct thread size. don't know why it is loose, maybe that is how it works.

anyways the coil would not work because you need a hole that is over 4mm for the coil to fit in, you wouldn't have enough room to make that hole on the case, the top flange of the sleeve is pretty close. another way is to re-tap the existing hole for a #6-32 screw (and don't forget to enlarge the hole on the button head too, 0.14" dia. would be enough). i did one for rc_alan last week and it seems to work.

316 s.s. screw is a bit too soft and i wouldn't use them on cooling head unless i have to.

data

Last edited by Data; 08-19-2004 at 12:46 AM.
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Old 08-19-2004, 12:20 AM   #8
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how about a 5-40? that is the only other tap i have here at the house, metric taps are pretty pricey around here.
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Old 08-19-2004, 12:44 AM   #9
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Quote:
Originally posted by GrandeGixxer
how about a 5-40? that is the only other tap i have here at the house, metric taps are pretty pricey around here.
#5 screw has an O.D. of 3.18mm, which is about the same size as the striped hole (3mm). even if you were able to tap it, the threads won't last long.

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Old 08-19-2004, 01:38 AM   #10
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so 6-32 is the way to go? i will try that. thanks for the help data. i will hopefully have some goos horsepower for the vegas race. tha omega/picco is getting a little tired and i am not buying another motor til the ritchey motor(plug) comes out. are you going to make it out there data? it would be great to meet you(not in a gay way.)
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Old 08-19-2004, 01:40 AM   #11
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Hell yes!

"Battleing Borgs and chasing after Orion females"
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Old 08-19-2004, 08:52 AM   #12
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GrandeGixxer,

To use the Helicoil inserts you bought, you will need the special tap for them.

McMaster Part #91709A355
Screw Thread Insert Tap M3-.5 Internal Thread, Plug Style
$ 16.22 Each

The procedure is to drill out the existing 3mm holes (McMaster's site calls for a 3.2mm bit).
Then you use the special tap above, insert the helicoil with some red loctite and your back in business.

You might want to enquire with McMaster's as these things usually come in a kit that contains a few inserts, the special tap and a tool for inserting the . . . errr . . . inserts. The same tool is also used for breaking off the tang. I'm not sure how you might get a fiddly 3mm helicoil in without this tool.

It looks like the cheapest kit is:
McMaster Part # 91732A942
18-8 SS Standard Helical Insert 10 PC Repair Kit, M3 Thrd, 4.5mm L, .5mm Pitch
$ 50.06 per Kit

. . OOOuuch.
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Old 08-19-2004, 12:02 PM   #13
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im just going to drill and tap it to 6-32 and call it good. easiest and cheapest way to go.
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Old 08-19-2004, 12:18 PM   #14
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Quote:
Originally posted by GrandeGixxer
im just going to drill and tap it to 6-32 and call it good. easiest and cheapest way to go.
you don't need to drill it, the striped hole should be big enough. but if you want to re-tap the other 3 holes to make them all the same, then you might need to drill the other 3 holes.

trying hard to stay away from vegas, let me know if you come down to LA someday. i will ask eddie the fish to show you his hacking technique.

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Old 08-19-2004, 01:18 PM   #15
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lol, will do data. as soon as my divorce goes through, i plan on doing quite a bit of traveling to races. i definatly want to check out crystal park and revelations. i am only 3 hours from la. im about 45 minutes south of fresno.
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