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bunging up hole in CI

I have miss drilled a steam hole in CI block

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Alan Wilkinson 112/02/2019 13:48:45
39 forum posts

What is the best way of plugging it ? make a Ci screwed plug and silver solder or a steel one and solder that which could then be peened over if it leeks. the hole is 4mm

Brian Oldford12/02/2019 15:12:34
684 forum posts
18 photos

What item is it going in to? Does it need to colour match?

Alan Wilkinson 112/02/2019 15:40:42
39 forum posts

the drilling was for asteam way so nothing going in. it will be painted over so matching is not an issue.

Rik Shaw12/02/2019 16:24:49
1354 forum posts
369 photos

I have this problem fast approaching but I intend using JB weld to fill the 'oles. I am also going to experiment using high build primer on the castings to - hopefully - smooth out some of the imperfections on some of the castings.


Edited By Rik Shaw on 12/02/2019 16:27:00

Buffer12/02/2019 16:38:41
165 forum posts
46 photos

Having gone to the effort of making the hole Is it worth keeping the spare hole.

mechman4812/02/2019 19:30:19
2724 forum posts
422 photos

I have used 2 part epoxy resin + cast iron filings / machined dust collected over a period of time; simply mix the resin & dust / filings together, fill the hole, ensure that you can get any residual air out of the hole, let it set overnight. Once set file / machine off level, worked fine for me on my S10V casting void.


p.s. threw the spare hole away, couldn't find a use for it.

Edited By mechman48 on 12/02/2019 19:31:12

not done it yet12/02/2019 19:38:45
4893 forum posts
20 photos

Seems like a simple case for a screw thread and some high temperature sealant - loctite or similar.

Enlarged and a cone with a coned screw - a bit like vehicle brake bleeds - might be a suitable. Any filler over the recessed item would suffice to cover the remaining surface before surface coating. Depends a lot on the depth/ space available/etc.

JasonB12/02/2019 19:45:09
18650 forum posts
2049 photos
1 articles

To plug the blind end of steam passages I tap them 40tpi and then turn and thread the end of a bit of matching material. Apply JBWeld and then screw in the plug until tight against where the make thread ends. Saw off once set and mill or file flush.

One here pluging the governor passage on the flat surface above the valve chest

Alan Wilkinson 112/02/2019 21:44:53
39 forum posts

will not silver solder be ok make a cast iron screwed plug then solder it???

IanT12/02/2019 23:29:17
1581 forum posts
145 photos

Cast iron is tricky to silver solder Alan - it can be done but it's not easy because the graphite content stops the solder 'wetting' I believe. I've never silver soldered or brazed a casting myself (as yet) - but many years ago the welding instructor at Maidenhead Tech bronze brazed a large cracked casting for me - and I can still well remember the swearing that accompanied the work. He managed it in the end but he said afterwards that it was a real b****!

I'd stick with Jasons' suggestion and use a screwed plug and JB weld - then just machine it smooth. Loctite works well when there's no heat involved but JB Weld will hold up better for this application.



Edited By IanT on 12/02/2019 23:30:40

Neil Wyatt13/02/2019 08:21:23
18140 forum posts
713 photos
77 articles

Silver soldering a plug into a large CI casting will be challenge as you need to get a lot of heat in and joint prep is important. A high temperature retainer will be fine.


Alan Wilkinson 113/02/2019 12:04:38
39 forum posts

Thanks to you all I have now ordered some JB weld and will go with your seggestions thank you.

Edited By Alan Wilkinson 1 on 13/02/2019 12:05:17

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