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Chris Preston

Welding Ferrets

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'Evening All, and Happy New Year to everyone.

We have some missing threaded studs to replace on the hull of our Ferret (for the muffler and right-rear fender), and as we'll be welding the studs directly to the hull armour, is there anything special we should use? We've also found some small hair-line cracks around the holes for the muffler mounting bolts that we'd like to address. Our welder is wondering if there's any special wire or pre-treatment to do before the welding. Any thoughts?
 
Cheers,
Chris Preston,
Victoria, BC,
Canada

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4 minutes ago, Diana and Jackie said:

A stud welding gun doesn't work but TIG does for the studs.

Diana

In REME workshops broken studs were renewed with stud welding guns, without an issues.

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A firm tried it on my Ferret and they just wouldn't hold. In the end they tig welded them on without filler wire.

Maybe the gun they used wasn't powerful enough?

Diana

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5 hours ago, Diana and Jackie said:

A firm tried it on my Ferret and they just wouldn't hold. In the end they tig welded them on without filler wire.

Maybe the gun they used wasn't powerful enough?

Diana

Hi Diana,

It was many years ago, and it was not an uncommon job with outside studs on Ferrets, Saracens, with seized nuts. The new studs were special for the job and I recollect they had something like a porcelain ring around them, which was broken away on welding. Don't think we had TIG in those days.

Richard

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Many Thanks Richard, Diana and Jackie for all your replies.

I'll forward them to our welder for his thoughts. Happy New Year to all of you.

Cheers,

Chris,

Victoria, BC.

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Is it an option to drill and tap the armour plate and screw in studs with some red Loctite?

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We've given that option some thought - we'll see what our welder thinks and take it from there. Thanks for your reply.

 

Cheers,

 

Chris, on the Left Coast.

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I've experimented with stud welding armour plate (took the driver's hatch down to a welding place) and the "normal" stud welders failed miserably, with the studs easily knocked off.

However their 3 phase stud welder did the job admirably. They did give me a sheet with the power needed but I don't know where that info is now. However it was just a matter of trial and error and in the end it was easy with the right device. They didn't have the correct size studs - had metric studs that were slightly thinner than the existing.

Another idea suggested was TIG welding a bolt that had its head ground down thinner. Drilling and tapping isn't anything that I'd consider.

JB Weld might be OK for hairline cracks that aren't overly structural, and it would be fun to try it for the studs but very much doubt it would be up to the task.

Cheers

James

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4 hours ago, Aussie said:

Backs up my experience with a 240V stud welder..

Diana

 

I've experimented with stud welding armour plate (took the driver's hatch down to a welding place) and the "normal" stud welders failed miserably, with the studs easily knocked off.

However their 3 phase stud welder did the job admirably. They did give me a sheet with the power needed but I don't know where that info is now. However it was just a matter of trial and error and in the end it was easy with the right device. They didn't have the correct size studs - had metric studs that were slightly thinner than the existing.

Another idea suggested was TIG welding a bolt that had its head ground down thinner. Drilling and tapping isn't anything that I'd consider.

JB Weld might be OK for hairline cracks that aren't overly structural, and it would be fun to try it for the studs but very much doubt it would be up to the task.

Cheers

James

 

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Thanks Everyone - excellent suggestions and feedback on this.

I'll speak with our welder on "the way ahead" for the welding, but I think we can do the TIG welding. His other work to date has been excellent.

Cheers,

Chris

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Hi Shrapnel,

Many Thanks for the info. We've dealt with our missing studs by drilling and tapping, and using Loctite to secure the studs. We'll see how this works, and re-visit the welding if we have to.

Cheers,

Chris Preston,


Victoria, BC,

Canada

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Chris,  that's good to know. Any problems? Did you use commercial drills and taps or did you have to go better quality?

Malcolm

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Hi Malcolm,

Apologies for the delay in replying - had to wait until I was back at the Museum today, and was able to speak with our welder.  We had no problem with drilling the plating, except for one hole where the armour had a backing pieces welded to it, and the hole was right over a weld. We used cobalt drill bits, and had no trouble tapping them after drilling. So far, everything's holding up nicely, but time will tell. In a couple of cases, we just drilled and tapped the hole, and then screwed a bolt in from behind, leaving a nice "stud" protruding  where needed. We used Loctite to ensure nothing loosens.

Cheers,

Chris

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Thanks, Chris. The cobalt drill bits are great. Bit pricey but much tougher than the gold coloured TiN bits. Took me 20 minutes and two TiN drill bits to drill a 1/2" drain hole in the aluminum hull of a CVRT and 2 minutes with a cobalt bit. 

I'm a bit surprised you had no trouble tapping. That's tough stuff. Were you using Canadian Tire-quality taps or something more industrial-quality?

Malcolm

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Hi Malcolm,

Glad it worked for you. Our welder did the work - he's also a metal fabricator with mill experience. I think he was using something better than what Canadian Tire sells for the tapping. That being said, only one hole gave him trouble tapping it, but in the end we got everything in that we needed to. 

Here's a link to our Museum's Facebook page: 

https://www.facebook.com/Friends-of-Ashton-Armoury-Museum-Victoria-BC-Canada-219752694888399/ . I'm the one hovering around the Ferret in blue coveralls, trying to look like I actually know what I'm doing.

Cheers,

Chris

 

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Agree with Shrapnel - stainless for welding.  Eutectic do 2.5 / 3.2 rods specified for joining dissimilar steels, or 'difficult to weld' steels, I think the number is 680S.  Very useful for odd jobs, not bad at joining cast iron too (cosmetic work - not if strength is not important). Also in wire form for MIG.  If you have cracks just vee out with a grinder / gouger and weld up with s/s.

With regard to drilling / tapping, armour plate works by 'work-hardening' - when a projectile hits the steel is initially plastic and deforms, reducing energy of the projectile, but then rapidly work hardens and resists further penetration.  That's why you see range hulls looking like they were made from plasticine and hit with stones!

We had (still have some) a stock of armour plate for building up excavator teeth / wear parts.  In order not to get caught out when doing general fabrication the trick was to drill a hole first to check if the plate was armour.  If it was armour it would drill fine to a shallow depth and then stop the bit in its tracks.  I did this once with 1/2" plate and a 1/4 drill went straight through so I thought 'ok this is mild steel', then spent a couple of days profiling out some big pieces, only to find the 1/2" drill failed.  If tapping you need to be very slow to minimise work hardening.

I believe drill bits for armour have a very shallow cutting angle - cutting tips are almost flat.

 

Forgot to add - grinding sparks off armour usually more an orange / red and smaller compared to yellow of mild steel - but not always that easy to distinguish, and like the drill test you can sometimes get 'caught out'!

Edited by N.O.S.

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12 hours ago, N.O.S. said:

I believe drill bits for armour have a very shallow cutting angle - cutting tips are almost flat.

Just chiming in with an agreement on this: Generally, I believe, the harder the material you're drilling, the shallower the point/included angle.
 

12 hours ago, N.O.S. said:

Forgot to add - grinding sparks off armour usually more an orange / red and smaller compared to yellow of mild steel - but not always that easy to distinguish, and like the drill test you can sometimes get 'caught out'!

It really isn't always as easy and clear-cut as one would like with spark tests, test-drilling, etc... It's almost like the material's out to get you, sometimes!

(You'd think, by now, I'd be able to recognise AR plate vs mild steel plate; working in a shop that does a lot of both, but I have mostly learnt to recognise it by how it nigh-instantly dulls the bit when I start drilling into it, after profiling it out, etc, etc. :$)

Good to know the methods for spotting armour plate, though; just in case!

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Great info. NOS and Tamber. Thanks.

Chris, can you ask the welder specifically what type of drills and taps he used? Hopefully it's not a trade secret. :)

Malcolm

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'Evening All,

Thanks again everyone for you replies to my original query on welding armour plate. In the end we ended up drilling and tapping to replace the missing studs. To answer Malcolm's question on what drills and taps we used, I'll quote our welder/metal fabricator directly: "I just used auto parts store cobalt bits, Butterfield taps, cutting oil and elbow grease". Hope this helps.

Cheers,

Chris

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Thanks, Chris. Cobalt drills are really tough sharp drills and I see Union Butterfield make good industrial quality taps. I think Canadian Tire-quality taps would break off in the hole and really mess things up.

It's a joke amongst mechanics that welders think everything can be fixed with a grinder and a welder. Since your welder used drills and taps, you gotta think this is the easier way to do it. ;) 

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'Evening Malcolm,

I'm a firm believer in using the right tool/part, etc for the job. We're lucky in that we have a welder/metal fabricator that seems to really know what he's doing. That being said, all of us were surprised at how smoothly that part of the job went.

Cheers,

Chris

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