UK Stationary Engine Forum
 

Go Back   UK Stationary Engine Forum > Main Engine Section > The Workshop > Tricks of the Trade

Reply
 
Thread Tools Display Modes
Old 12-08-12, 08:32 PM   #21
oldchadders
Forum Supporter 2011
 
Join Date: Aug 2009
Location: Adstock, Buckingham
Posts: 831
Default

Quote:
Originally Posted by Grendel View Post
That's exactly how I do it.
I do think that tapping to the next size is much stronger than using one of these helicoil jobs.

Cheers,

Hubert
A correctly fitted Helicoil (or similar) is said to be stronger than the original thread. I have used them many times, particularly in aluminium cylinder heads to strengthen manifold fixings.
__________________
Peter
Douglas VS25; Douglas SV (both under restoration)
oldchadders is offline   Reply With Quote
Old 12-08-12, 09:17 PM   #22
Grendel
Forum Supporter 2012
 
Grendel's Avatar
 
Join Date: Feb 2012
Location: The Netherlands
Posts: 800
Default

Right, "said to be,....."

I have used them as well and because they are steel, they are much stronger than aluminium, but I am convinced that they rip out sooner than if you had gone one size bigger.
I don't like them at all, but they can be used without trouble for not too demanding applications.

Cheers,

Hubert
Grendel is offline   Reply With Quote
Old 12-08-12, 09:38 PM   #23
martinpaff
Admin Team
Forum Supporter
 
martinpaff's Avatar
 
Join Date: Mar 2007
Location: Lincoln, UK
Posts: 11,249
Default

Quote:
Originally Posted by Grendel View Post
Right, "said to be,....."

I have used them as well and because they are steel, they are much stronger than aluminium, but I am convinced that they rip out sooner than if you had gone one size bigger.
I don't like them at all, but they can be used without trouble for not too demanding applications.

Cheers,

Hubert
Wrong!

Helicoils are (if inserted correctly) invariably stronger than the host material. For this reason they are always specified for female threads in the aviation industry where a failed thread could lead to something drastic - not just in alloy but also in some quite exotic materials that are quite capable of holding a thread themselves. They have the added benefit that if a thread is spoiled the insert can be replaced.

MP
martinpaff is offline   Reply With Quote
Old 13-08-12, 05:49 PM   #24
Coal Miner
Forum Supporter 2011
 
Coal Miner's Avatar
 
Join Date: Jun 2008
Posts: 620
Default

On my current restoration project I had the misfortune to shear off three out of four studs (I couldn't beleive that I was so unlucky!). I looked at Easy Outs; surprisingly I could buy a set of five for 1.59p. Hardly a quality engineered item! So they were rejected and the problem was solved by welding nuts onto the studs and then heating around the stud with oxy-acetylene. Eventually they all came out, but the secret is plenty of heat.
Barry.
Coal Miner is offline   Reply With Quote
Old 13-08-12, 10:23 PM   #25
boingy
Member
 
Join Date: Aug 2010
Location: gloucs, UK
Posts: 63
Default

You have just reminded me of an old engineering definition of screw extractors:

"Screw extractors: A tool which allows the discerning engineer to replace a relatively soft broken screw with a short length of the hardest material known to man."

I tend to centre punch very carefully then drill with ever increasing RH drills until I just start to break through one edge (because you are never quite in the centre). I like the LH drill idea though.

As for helicoils, I've never used them but I know others who swear by them. They always seem scarily expensive for what they are.
__________________
Ian
boingy is offline   Reply With Quote
Old 14-08-12, 08:25 AM   #26
Pugdud
Forum Supporter 2013
 
Join Date: Mar 2009
Location: Winslow Bucks
Posts: 803
Default

I agree with Barry's method, its only useful though if you have some potruding bolt to weld onto.
To judge where the exact centre is, when centre punching the bolt, is difficult because the thread pattern guides you off centre all the time. Careful positioning of the early drill hole is the most important part of the operation. After that its plain sailing.
Tony.
Pugdud is offline   Reply With Quote
Old 21-08-12, 07:31 PM   #27
110samec
Senior Member
 
110samec's Avatar
 
Join Date: May 2011
Location: Anglesey, North Wales
Posts: 325
Default

Machine marts got a set of extractors for around 12 if I remember correctly.
__________________
Petter PAZ1, Suffolk 75G14, Ruggerini RF120 + fire pump,1976 Series 3 Land Rover
110samec is offline   Reply With Quote
Old 22-08-12, 08:59 AM   #28
Coal Miner
Forum Supporter 2011
 
Coal Miner's Avatar
 
Join Date: Jun 2008
Posts: 620
Default

But this is my point 110samec:- If I am going to use an extractor I would like it to be well engineered and made out of the best quality steel known to man so that it doesn't break when I start to lever on it with a length of scaffold pole! Therefore I would expect to pay more than 12 each rather than for a set. What do others think?
Barry.
Coal Miner is offline   Reply With Quote
Old 22-08-12, 09:16 AM   #29
110samec
Senior Member
 
110samec's Avatar
 
Join Date: May 2011
Location: Anglesey, North Wales
Posts: 325
Default

I see what you mean. I've ordered a set anyway as I need to use one on an allen bolt thats solid so when they arrive I'll tell you if they work (or not)
__________________
Petter PAZ1, Suffolk 75G14, Ruggerini RF120 + fire pump,1976 Series 3 Land Rover
110samec is offline   Reply With Quote
Old 22-08-12, 05:30 PM   #30
Pugdud
Forum Supporter 2013
 
Join Date: Mar 2009
Location: Winslow Bucks
Posts: 803
Default

Quote:
Originally Posted by Coal Miner View Post
But this is my point 110samec:- If I am going to use an extractor I would like it to be well engineered and made out of the best quality steel known to man so that it doesn't break when I start to lever on it with a length of scaffold pole! Therefore I would expect to pay more than 12 each rather than for a set. What do others think?
Barry.
Well I think that I never managed to get a stuck bolt out with any type of easyout, during the whole of my engineering life, incidently I never broke an easyout either, - though I did soon give it up as a bad idea. It will be interesting to hear the result - I hope its good.
For the City and Guilds one year, I think it was 1962, the examiner tightened a bolt into a test piece and broke it off flush. Neither the students or the examiner could remove it, the test was deemed impossible and none were marked down for it.
Tony.
Pugdud is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +1. The time now is 07:56 PM.


Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.