Topic: Ideas needed unusual project (Read 8656 times)

ukmike · « **on:** January 31, 2018, 02:34:08 pm »

Hello.
I need some ideas on how I can hold exhaust flanges in position to enable silver soldering.
It can't be done in situ due to the heat required.
The photos show the problem that I have; one flange is partly shaped and nearly fits, with a little more filing a good fit should be achieved.
The other flange is without any shaping.
The transom is curved but also angled outward so the arc described at the top of the flange is different from the bottom, compounding the problem.

My thought is to fit the completed exhausts in place on the transom then use fire cement to keep the flanges fixed, when set, remove and solder from the rear.

Here are the photos.

Netleyned · « **Reply #1 on:** January 31, 2018, 02:40:36 pm »

Make another sacrificial transom shaped
the exact same.
Make up the pipes and flanges on that
then insert through the holes in the
real transom.
Just my idea on it.
Ned

ukmike · « **Reply #2 on:** January 31, 2018, 02:52:03 pm »

Thanks for that Ned.

An awful lot of work and very complex.

Have added my idea to the post, have a look and see what you think ?

Mike.

Netleyned · « **Reply #3 on:** January 31, 2018, 03:10:32 pm »

Fire cement might work, but
will it adhere well to metal?
When you heat the metal it will
expand at a different rate to the cement.
Worth a try though.
Ned

tigertiger · « **Reply #4 on:** January 31, 2018, 03:32:15 pm »

You could make a plaster mould from the transom. Then mould a dummy transom, again in plaster, and drill for the pipes. Then use the dummy plaster transom to hold the pieces while soldering.

Mark T · « **Reply #5 on:** January 31, 2018, 04:46:49 pm »

I would mark both peices so that they can be correctly aligned after removal from the transom. I would then drill a hole into a vermiculite block at roughly the same angle as the joint and the same diameter as the exhaust. This would allow you a rough alignment which could then be wiggled to exactly where you needed the joint to be as vermiculite is quite soft. Then you can just solder away till your hearts content

Mark T · « **Reply #6 on:** January 31, 2018, 04:49:47 pm »

Vermiculite block http://www.cupalloys.co.uk/brazing-ancillaries/index.asp

ukmike · « **Reply #7 on:** January 31, 2018, 06:23:43 pm »

Quote from: Mark T on January 31, 2018, 04:49:47 pm

Vermiculite block http://www.cupalloys.co.uk/brazing-ancillaries/index.asp

Thanks Mark.
Could work with a bit of fiddling but at £13 delivered it's a little too expensive.

Mike.

BFSMP · « **Reply #8 on:** January 31, 2018, 07:02:48 pm »

https://www.amazon.co.uk/J-B-8297-HighHeat-Epoxy-Putty/dp/B007PP26RI

Netleyned · « **Reply #9 on:** January 31, 2018, 07:19:21 pm »

Might be a tad difficult to remove
after silver soldering Jim.
Ned

JimG · « **Reply #10 on:** January 31, 2018, 07:35:18 pm »

Could you use a tapered mandrel to expand the tube to be a tight fit on the flange? This might hold it while you solder it.
Jim

skierdive · « **Reply #11 on:** January 31, 2018, 07:47:34 pm »

As a beginner, could you please explain why the flange needs silver soldering to the pipe?

Will the soldered joint be on the "outside"? If so, it will have to be a very neat job as it will be on display for all to see.
( I'm sorry, I've just re- read your post and it does say you will solder it from the rear, so please ignore this question)

Does it need silver soldering at all? Or could you not just put fixing pins through the holes in the flange to secure it to the transom.

Finally, How hot will the pipe get? Is it an engine exhaust, or water cooling outlet? I was just wondering if you were using the flange as a "heat sink" or is it just for decorative purposes?

Sorry, lots of questions as usual, Ian

ChrisF · « **Reply #12 on:** January 31, 2018, 08:11:42 pm »

Hi

Could you use some heat resistant tape stuck to the transom?

Do the soldering and then remove the tape? Quick Google found some at around £5 per roll though for more than you need.

Chris

ukmike · « **Reply #13 on:** January 31, 2018, 08:39:13 pm »

Hello Ian.
The exhausts are cooling water outlets 12mm steel tube with 21mm steel flanges to be held on using 1.5mm X 15mm stainless screws. The build is a very near 1/7th scale reproduction, (hopefully).
The soldering will make watertightness far easier to achieve than having separate parts, which could and probably would, eventually leak due to vibration. Also the full size example was done this way for that reason.
The assembly will be chrome plated when finished.

Mike.

Hope that helps.

Mike.

ukmike · « **Reply #14 on:** January 31, 2018, 08:47:19 pm »

Quote from: ChrisF on January 31, 2018, 08:11:42 pm

Hi

Could you use some heat resistant tape stuck to the transom?

Do the soldering and then remove the tape? Quick Google found some at around £5 per roll though for more than you need.

Chris

Hi Chris.
The melting point of my s/solder is about 650C and the flame nearer 1200C. I don't know of any tape
that will stand that but please let me know if you do.

Mike.

ChrisF · « **Reply #15 on:** January 31, 2018, 08:56:46 pm »

Whilst carrying out the soldering insitu will obviously provide the greatest accuracy I'm guessing, as I'd be, that you are nervous of doing that!

As you say building a replica of the transom is time consuming and no guarantee it will be exactly the same, so what about just replicating an area a little larger than the flange in say solid timber?

Solder it up and if not quite right unsolder it and try again. No extra expense in doing this.

derekwarner · « **Reply #16 on:** January 31, 2018, 10:25:27 pm »

Well Mike

.....just a few left of centre thoughts

1. galvanic chrome plating will not plate more than a few mm into either end of the tube, so will leave the majority of the tube ID as raw steel
2. galvanic chrome plating deposit is porous.......if left for any extended periods with water of any quality will rust - dissolved gases would be problematic
3. electroless nickel plating will plate the entire bore surface
4. an electroless nickel plated surface has Zero porosity and will be impervious to the water with even with dissolved exhaust gases - however flushing would be recommended post use
5. is it 100% imperative that the exhaust tips are mirror chromed/nickel plated finish?....could the tips be chemically blackened?

If the last part of 5. were possible, you could substitute brass tube & brass bolted retaining disks?..........brass components could also be soft soldered

The transom appears to have curvature in both planes .....so the disk rings unless counter-bored into the transom would require a compound dished internal surface

Either way, dummy port & stdb transom surfaces will be required...complete with a few tapping's, to ensure the support disk rings are aligned correctly

Derek

skierdive · « **Reply #17 on:** January 31, 2018, 10:47:53 pm »

Thank you, Mike

Ian.

ukmike · « **Reply #18 on:** January 31, 2018, 11:49:06 pm »

Quote from: derekwarner_decoy on January 31, 2018, 10:25:27 pm

Well Mike .....just a few left of centre thoughts

1. galvanic chrome plating will not plate more than a few mm into either end of the tube, so will leave the majority of the tube ID as raw steel
2. galvanic chrome plating deposit is porous.......if left for any extended periods with water of any quality will rust - dissolved gases would be problematic
3. electroless nickel plating will plate the entire bore surface
4. an electroless nickel plated surface has Zero porosity and will be impervious to the water with even with dissolved exhaust gases - however flushing would be recommended post use
5. is it 100% imperative that the exhaust tips are mirror chromed/nickel plated finish?....could the tips be chemically blackened?

If the last part of 5. were possible, you could substitute brass tube & brass bolted retaining disks?..........brass components could also be soft soldered

The transom appears to have curvature in both planes .....so the disk rings unless counter-bored into the transom would require a compound dished internal surface

Either way, dummy port & stdb transom surfaces will be required...complete with a few tapping's, to ensure the support disk rings are aligned correctly

Derek

Hi Derek
The tube is non corrosive as it is as "Precision steel tube", so the supplier tells me.
It's coated with a grey ultra smooth stuff both inside and out which has to be removed where soldering and chroming is to be done, only the external parts will need plating, also, the inside of the tailpipe will be painted red.
Would have preferred to use brass but 12mm tube seems to be unobtainable here.
The tubes are 150mm long and the flanges 21mm so even soft soldering bass would be impossible to do in situ as the amount of heat needed would have been unacceptable to me, there is no way that I would risk damaging the transom.

Mike.

bfgstew · « **Reply #19 on:** February 01, 2018, 12:03:16 am »

I shall try and explain what I would do.

Between the transom and last frame add a block of timber, drill through for you exhaust pipe then counterbore to take the flange piece. Instead of just a thin piece for the flange as you have now use a longer length with screw holes in already, so it is proud of the transom. This will then require careful filing to get the correct angle to suit the transom form, once done, mark the pipe, remove, solder, plate etc etc. Once done it should just slot in nice and snug.

Hope that helps?

Stewart

warspite · « **Reply #20 on:** February 01, 2018, 04:27:21 pm »

Or, drill a hole to suit the O/D of the pipe into a block of wood, then place slivers of wood between the block and the transom to level the bored hole to the correct angle, the final slivers allow for the flange. Glue the lot together (not the pipe), check and file to suit, plug the outside end of the hole to make the pipe stay at the correct length out of the transom, check and adjust as necessary, (a jig) once happy fit the pipe and flange as tested, solder in the block and adjust if necessary.

tonyH · « **Reply #21 on:** February 01, 2018, 08:55:52 pm »

I presume you're using the 650 degree solder for a reason but would it not be feasible to use the 305 degree C version from Cupalloy?

If it's possible then all you'd need to do is insert a layer or two of thermal cloth between the fitting and the transom to reduce the charring.

I've used it on odd occasions and it's rather strong.

Tony

derekwarner · « **Reply #22 on:** February 01, 2018, 09:22:02 pm »

Mike.....whatever you do, don't buy a car from this bloke

"The tube is non corrosive as it is as "Precision steel tube", so the supplier tells me.
It's coated with a grey ultra smooth stuff both inside and out which has to be removed where soldering and chroming is to be done"

The precision bit is the diametrical tolerance on the diameter of the tube & the ultra smooth grey surface is chemically phosphated & oiled ...steel is steel & it tends to rust..................

[the oiled surface would probably provide about 15 minutes of resistance to a damp mist]

K&S metals list both 12.0 & 12.7 mm OD brass tube

Derek

Brian60 · « **Reply #23 on:** February 01, 2018, 10:34:05 pm »

Soft solder in place, then remove pipe. Hold together on the bench with fire cement then silver solder. Clean up and refit.

ukmike · « **Reply #24 on:** February 01, 2018, 11:47:24 pm »

Derek.
No 12mm k&s brass tube to be found here, 10mm max, although you are quite correct, it is listed on the U.S.site. But at less than 1/2mm wall thickness I wouldn't even consider it. All of the materials for the job have been decided upon and gathered now and rust certainly will not play a part in the completed project.
BTW. No sign of oil anywhere !

Mike.

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Author Topic: Ideas needed unusual project (Read 8656 times)