Getting dings out of brass tubing?

[Ian ParkinParticipant @ianparkin39383]

[Ian ParkinParticipant @ianparkin39383]

I'm on with restoring an old kismet pump hopefully to use as a quiet pump to top up my car and bike tyres.

The cylinders (its a duplex type) have a few dings in them which in the whole scheme of things dont really matter as it has as standard leather seals which will conform to the slightly distorted inner surface.

However how would i go about removing the dings?

Also does anyone know if i could retrofit modern seals? What types do i need to look for my worry is that with infrequent use the leather will dry out and need constant attention oiling etc

[Jeff DaymanParticipant @jeffdayman43397]

I saw a TV show some time ago, a "How its' Made" episode, on repairing brass musical instruments. They showed a technician repairing the bell of a badly deformed saxophone with a large steel ball on the inside and a cloth-wrapped very large neodymium rare earth magnet outside. He rolled the ball back and forth inside the instrument using the magnet outside it, which took out the dents and worked the bell back to perfect condition. Probably tremendous skill and much practice is needed for such fine work, but maybe it would be worth a try in your tubes if they are not too thick. It may also be possible to find a close fitting steel ball to go in the tube and force it through with a press to push the dents out. Hope the ideas help. JD

Edited By Jeff Dayman on 02/08/2017 19:35:51

[Ian ParkinParticipant @ianparkin39383]

I did think about turning a thick steel washer about 1" long with a large radius on its outside rim the exact size of the tube and fastening that to a length of studding and push it in and then i can use the studding to extract it if need be?

Do i do it cold or warm it?

[vintagengineerParticipant @vintagengineer]

Balls are the answer! Try and get a bag of steel ball bearings the same size as the ID. Fill the tube with balls and then tap them down and keep forcing the balls through.

[Clive FosterParticipant @clivefoster55965]

According to Guy Lautard in "Strike While the Iron is Hot" such dents can be ironed out of hydraulic cylinders using a nicely fitting solid spigot with a short taper on the end. The taper is machined to a D shape. To remove the dent the tool is bought up to the dent and gently turned whilst the outside is tapped with hammer. Seems no good reason why it shouldn't work on brass too. Age hardening may be a factor tho'.

OK the book is fiction but Guy was usually pretty good on machining / metalwork techniques and there is no good reason for using up best part of page over an impractical technique. I imagine there is considerable, glossed over, craft skill involved concerning the angle of the taper, how much to engage in the dent and how hard to tap.

When you get down to the ideas are essentially the same as panel beating to remove dents which always seems to revolve around striking the intuitively wrong side of the dent!

Clive.

[Ian ParkinParticipant @ianparkin39383]

Whatever i put in has to come out of the end it was put in

The large tube is 80mm or so so balls that big will be spendy

[Mark P.Participant @markp]

Could you not fill the dings with lead?
Mark P

[martin perman 1Participant @martinperman1]

I've removed dents from tubes with a similar method already mentioned, I make a steel bullet with the nose radiused and the other end drilled and tapped to screw in threaded rod, polish the bullet to remove cutting marks and gently tap into the tube whilst tapping around the outside with a plannishing hammer, smear tallow on the bullet and soften the brass with heat otherwise it will split.

Martin P

[Neil WyattModerator @neilwyatt]

See MEW 258 to read how it's done in flute repairs!

In simple, put a tube up the centre and tap the ding out, except it's not quite as easy as that.

Neil

[roy entwistleParticipant @royentwistle24699]

Perhaps some of our gunsmith friends could enlarge on how they remove dents from shotgun barrels

Roy

Edited By roy entwistle on 02/08/2017 21:45:02

[Matthew ReedParticipant @matthewreed92137]

For trombone slide repairs and the tuning slides of other brass instruments, I use a 'bullet. Slug of steel urged on the lathe to be a tight running fit in the good part of the tube, shaped like a bullet, with a hole through. Mount on a slide hammer: pieces of studding rod, nuts to secure bullet (two either side, with a bit of play) and whatever lump of heavy scrap you have turned round and bored out to suit. Two more nuts either side allowing 10" play( or turn some oversize nuts, as these take the real force). Assemble in tube, hammer the bullet up to and through the dented part, then back through, repeat etc. Brass is springy so you will need to pass it through several times.

Helps to polish the bullet with emery cloth and lightly grease, and two,sizes of bullet can also help.

Edited By Matthew Reed on 02/08/2017 21:40:05

[Anonymous]

Posted by roy entwistle on 02/08/2017 21:29:01:

Perhaps some of our gunsmith friends could enlarge on how they remove dents from shotgun barrels

Roy

Edited By roy entwistle on 02/08/2017 21:45:02

Wouldn't want to be the one to fire it after someone knocked a barrel dent out I suppose technically you could have it reproofed but I doubt you'd find someone who would do it or has done it.

[“Bill Hancox”Participant @billhancox]

This is the most common method for shotgun barrels. **LINK**

[Sam Longley 1Participant @samlongley1]

Posted by Mick Berrisford on 02/08/2017 22:36:17:

Posted by roy entwistle on 02/08/2017 21:29:01:

Perhaps some of our gunsmith friends could enlarge on how they remove dents from shotgun barrels

Roy

Edited By roy entwistle on 02/08/2017 21:45:02

Wouldn't want to be the one to fire it after someone knocked a barrel dent out I suppose technically you could have it reproofed but I doubt you'd find someone who would do it or has done it.

What you do is cut the barrel off just at the dent & flog it to some pykies for their "post office collection trade"

[Mick B1Participant @mickb1]

Metallic cartridge reloaders do this kind of reforming all the time when neck expanding cartridge cases. You need a plug with radiused lead-in, sized to the ID of the cylinder, some (eg) molybdenum grease and a means of forcing the plug through and withdrawing it if you meet problems. I used the tailstock of my lathe when de-denting some antique telescope tubes.

[Ian ParkinParticipant @ianparkin39383]

Just been measuring for seals purposes and the larger size has a wall thickness of 3mm and the smaller 2mm

Will the dings/dents spring out or should i heat locally when the plug is near?

[roy entwistleParticipant @royentwistle24699]

Sam and Mick Iv'e known quite a few shotguns get dents, all were repaired successfully and were quite safe to use without being reproofed. In fact you could not see where the dent had been

Roy

[J HancockParticipant @jhancock95746]

For your air pump only , I think filling the dent in the shaft with soft solder is the more simple solution.

[Ian ParkinParticipant @ianparkin39383]

J Hancock

The ding in the outside isn't the prob is where its on the inside

[JohnFParticipant @johnf59703]

Ian you are spot on with the plug idea but it needs to be much longer than 1" I would suggest around 2.5" to 3" this will keep it straight in te bore. D & T for a withdrawal handle of course. Then as others have said tap around the OUTSIDE of the dent as you pushed the former in, this will raise te dent without expanding the parent metal. It can also be useful to use a dolly to tap with the hammer rather than sticking the metal direct.

Gun barrels removing dents is common place I have done probably 1000's over the years but if the dent was severe I would recommend or insist the gun was submitted to re-proof for everyone's protection.

[Ian ParkinParticipant @ianparkin39383]

Well i tried the plug idea but it just went past the dings with lots of force and then came back out with much pulling and the dents remained

So i made a plug to be a nice sliding fit and cross drilled a 10mm hole and a 10mm tapped hole in line with the plug then a 10mm da plug of silver steel with a taper on one end and ground to match the outer dia place the plug in the tube aligned the pusher and a long Allen key winds the peg out pushing the dent out…quite satisfying watching the dent slowly pop out..never to spring back i hope

[HacksawParticipant @hacksaw]

Brilliant thinking

[MWParticipant @mw27036]

I think very deep dents are inevitably not going to look the same again no matter how much you push out. The best you could do at that point would be to try and hide it and smooth it into the rest of it.

Michael W

[Ian ParkinParticipant @ianparkin39383]

i'll post photos when its done

The wall thickness is plenty so it will polish out easily

I'm more concerned with teh pump working than looking as new

Edited By Ian Parkin on 10/08/2017 22:05:40

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