doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Fitting hammer castings.

Would appreciate some advice regarding fitting of hammer castings.

I have some castings from peter dyson here in the UK.
I have cleaned up all the sprue and stuff left over from casting.

I want to know how members would go about fitting these hammers as i am in several minds.

My idea would be to drill a hole the same size as the width of the square axle, then to place the hammer over the top of the axle and not the positioning of the flats and file them in. Fortunately my needle files are the exact width of the axle square and there fore putting a bit of a taper into the square hole should ensure a good fit.

However what is obvious is that one cut too many or even slightly getting the angles wrong is going to result in a rubbish fit which would then either need to be welded and refiled or peened, and i don't want to do either if i can avoid it.

I could take the locks apart but then I'm not going to know what angle the axle needs to be at to ensure the flats are correctly filed. Even if i do so the tumbler is a small fragile part so gripping it in a vice so i can try and smoke the hammer on to the axle is not going to be all that easy either.

I am assuming there is a simple ingenious way that i can do this which is why I'm asking here before i start ordering replacement replacements.

Over to you,

Thanks in advance gents.

I have never had the pleasure of performing this operation and hope I never have to. However, might as well get it from those who knew how it should be done. This is from The Gunsmith's Manual, by Stelle and Harrison, 1883. If interested, there are used copies available at www.amazon.com for about $10.00. Lots of great tips for our interests.

Good luck!

Much obliged good sir for the efforts you went to to provide me with the right answer.

I have two sets of pinfire hammers and one set of percussion hammer to fit so it will be worth while to make the tool, i will make the tool and report back.

Thank you very much!

Just bought some 5mm x 5mm steel square stock to practice making up the drift.

http://www.ebay.co.uk/itm/METRIC-KEY-STE...=item417728546d

Part of me doesn't want to be defeatist and back in the day most gunsmiths made their own tools; the other pat of me realizes that the cost of buying a commercially made broach divided up between the 6 hammers i need to fit makes the broach about �20.

�130 quid is a lot to spend on a square hole.

http://www.steelmans.co.uk/?92,5mm-square-broach

I think i will have to try first, even if my home made broach completely cocks up i can order a new casting for less than the cost of a commercial broaching tool.

I'd consider it money well spent for the enjoyment and learning in it...!

Demonwolf the square in a guns hammer casting is not made with a conventional modern broach which cuts the hole be it square round or oblong. The method is a little more brutal and makes more sense when you hear the explanation I was given when I first wanted to fit new replacement hammers to a gun. Contrary to what we may think the square hole in the hammer boss on old Brit guns is slightly tapered from the back to the front of the hammer, and is actually swaged into a tapered square from a round hole drilled in the boss starting from the back in the correct orientation to enable the hammer to sit in its correct position. So let�s get the complications of hammer fitting in proportion they were fitted by hand by a normal man and the method used has worked perfectly for hundreds of years and it is not rocket science.
Firstly you need to make a smooth square tapered punch (can also be called a broach) that must be harder than the hammer�s metal so you will need to purchase some round silver steel which is heat treatable steel (US they call it drill rod) cost of about �3. Having obtained the silver steel you will have to file it to a square about 40mm long (1� inches approx.) tapering between about 2 to 4 degrees having the hammer mounting square size about three quarters the way along the punch from its smallest dimension then harden and temper it (this is not hard to do look on u tube). Contrary to what we may think the square mounting hole in a hammer on old Brit guns and others is slightly tapered and the reason for it is that because of the taper as you tighten the hammer retaining screw the mounting square is forced to the point that it is tight in the hammer hole, and should it work loose with use you re-tighten the retaining screw to move the hammer slightly on the taper and so tighten.
Its use is simple you drill a hole in the hammer boss slightly smaller than the hammer mounting square and introduce the punch starting from the back of the hammer boss making sure that the square you are making is in the correct orientation for the correct hammer position. Hammer the punch into the hole while supporting he hammer on a metal surface with a hole that will clear the punch as it moves through, this will compact the metal improving its density and of course shape the hole, as you move the metal with the punch you can try the hammers fit on its mounting square. Sometimes you may have to adjust the size of the hole by using a file to remove some metal to help things along but it should be more hammer than file.
I hope this all makes some sense. damascus

Excellent explanations, but one thing more. Be certain that the resulting hole in the hammer is smaller than the square on the tumbler shaft. Reason is that you do not want the screw, when tightened, to draw the outer face of the hammer all the way down to the end of the tumbler shaft. In order for the screw to be able to keep the hammer tight on the taper, there must remain a slight space between the back of the screw head and the end of the tumbler shaft. If it ever reaches the point of being flush, the hammer will loosen with use because the screw no longer has "purchase".

SRH

Right o, all sounding simpler now, square tapered punch will be made and the holes made - I will report back, i have some high carbon steel coming. No simple method behind getting the alignment just so other than just going steady? could do with a fail safe way to get the position of the square axle on to the hammer?

Funnily enough i found a tapered square punch in the drawer, marked it at the point the originals passed up the punch then gave the hammers a good pounding, worked a treat, one set of the pinfires are well and solidly fitted now. Thank you.