Four opposing right-angles

[GNJC]

Hello all,

I am having trouble making a flywheel for a spit engine (clock jack in the US).

The design is a simple cross with squared hole in the centre; but, I only want to use methods and tools available to a smith pre-1780; so no modern cutting or welding techniques.

I have made many pieces of work where an accurate and crisp right-angle was needed inside and out, no problem. But now I have to accurately form four opposing right-angles.

Having split my flat stock (1/4"x3/4") at both ends and opened it to a cross shape, when I try to forge the centre and get accurate right-angles, each time one is done correctly the forging of the others 'offsets' the recently completed good one.

Having now made many attempts, and an equal number of failures, I thought I'd ask for advice on impoving my forging (before resorting to oversizing and a ridiculous amount of filing!).

All help gratefully received.

G.

[John B]

Why not cut it out with a hot cut from a plate if its only 1/4" thick ?

[MattBower]

Maybe I'm not understanding the problem correctly, but why can't you punch a hole, drift it out with a slightly undersized, precisely made square drift (drift and punch could probably be one, in fact), then finish with a little filing?

[ThomasPowers]

I'm having trouble envisioning what you are truing to do to but my *guess* would be: Take 2 straps, forge weld at the overlap, punch round hole, drift square.

Remember that a lot of kitchen stuff was not fancily finished---though the preservation bias is toward the fancy ones. The plain using ones often were used till they wore out and then recycled. The flywheel need not be as precise as one for a clock and at the slow speeds involved will not cause a lot of imbalance issues.

[GNJC]

Hi,

Thanks for replies; ThomasPowers, I agree that a lot of the kitchen stuff made was pretty rough, but this flywheel is to sit on top of the spit engine's worm and act as a regulator; it really needs to be well balanced to prevent an eccentric rotation.

The attached photo' shows an ideal finished article. Getting a hole of the correct size in the middle is no problem for me, the problem lies in getting the cross with 4 x symmetry.

My camera is not working at the moment, when my wife get's back I'll post my latest poor effort to show the 'offset' problem.

G.

[MattBower]

OK, I did misunderstand the problem. You're having trouble getting the cross exactly symmetric. Could you make a sort of bending jig to help you adjust the arms to exactly ninety degrees?

[GNJC]

Hi Matt,

A jig is fine for arm allignment, I used that after my first few attempts with just a hammer and anvil. But it only worked for first one angle and then it's opposite; once I started on the adjacent (diagonally opposite) arm, the corners near the centre 'shifted'.

Whereas with a normal right-angle my corners are sharp and crisp, the result of this shifting/offsetting is a rounded corner. That, in itself, is not a problem, but not having the arms properly opposite one-another is.

Having now got hold of a working camera, the two pic's below should demonstrate the problem; in the centre of the wheel is a piece of tube formed to fit on the worms square vertical shaft.

Regards,

G.

[John B]

I think you need a little more patience when adjusting the arms for square. This is a fAirly simple and straightforward challenge, though your material sizes may make it more awkward.

First split and open up the arms, then over the edge of the anvil coax the opposing 'arms' into alignment (Like using a side set and a set hammer)this will bring the arms into the required position

Alternatively, what may assist to get them spot on is to use a monkey tool and a bolster, that way you are aligning the arms with each other, and you will be able to get them square by working them alternately

Open the ends to the approximate shape, when hot place one arm through the bolster and use a monkey type tool (this could be a suitable size piece of pipe) to bring the arms on the bolster in line,

Repeat for the other arms, you may have to do this a couple of times or more until you are satisfied with the result, you can then punch and drift the centre.

Good luck with it

[HWooldridge]

I agree that splitting and spreading one piece is a perfectly acceptable method and your original pattern does not look forge welded.

I'd suggest clamping one leg in your vise close to the cross (horizontally so the view from above will be the same as your pictures, i.e. "plan view"). If you are right handed, put the offset to the right so you can drive it to the left. A torch would be better to pinpoint the heat but a forge can be used with a watering can to cool the spots you don't want to distort. Take a heat, clamp in the vise and swat it near the juncture. The opposing legs may bend out of square a bit but you can continue to move the piece in the vise and straighten as you go. The piece you made should straighten up in 2-3 heats.

[Iron Clad]

If you are good at forge welding, why not just forge weld two bars in the centre and punch and dift the centre hole? This seems the most economical and quick way.

[ThomasPowers]

I already suggested that and got shot down.

[Iron Clad]

That's right Thomas I see you did post that already! So would you agree that welding two bars together (overlaped in the center) would be the probable traditional method?

[ThomasPowers]

Yes, if not sand cast in brass. Real wrought iron welds very nicely indeed.

I need to re-read Moxon to see how he has it done.

[Iron Clad]

Moxon ?? I have a lot of blacksmithing books but I don't recall this one. Moxon must be the author, what is the book?

[ThomasPowers]

Mechanic Exercises, Joseph Moxon; *don't* get the Vol 2 one on Printing; the smithing info is in the first volume!

Has how to set up a smithy, what kinds of iron is good for what, general instructions on how to do things and a project or two of which a jack is one of them. Originally published in 1703 most of the info really dates before that.

Astragal Press did a nice re-print. I found a copy in a used bookstore in Van Buren AR about a dozen years ago...yes we raid all the used bookstores when we are traveling on vacation...

[GNJC]

Hello,

I have yet to get a chance to try again, work and a very pregnant wife (baby preparation!) are taking up nearly all of my time.

Some time ago, somewhere on IFI, I have posted scans of Moxon's book showing his full instructions for making a spit engine / clock jack. The fly-wheel is covered in only a paragraph, stating that the number and length of arms controls the speed of turning.

Having examined several fly-wheels - dating from the late seventeenth to early nineteenth centuries - none showed visible signs of welding, hence my wanting to split and forge it.

Sadly I think an earlier post hit the nail on the head, I need to spend a great deal more time working on it. I'll post a picture when I finally get it right!

Regards,

G.

[dkunkler]

Moxon ?? I have a lot of blacksmithing books but I don't recall this one. Moxon must be the author, what is the book?

You can download a pdf version from googlebooks here.
http://books.google.com/books?id=t_IRCzjTf08C&printsec=frontcover&dq=moxon&ei=Q0D0S4mtBaWCywTlvrjUCA&cd=1#v=onepage&q&f=false

[Sam Thompson]

Can't you just saw it out of a piece of plate?

[GNJC]

Hello Sam,

Yes, could saw it from plate, but want to make it the original way. I just need time and practice (as with everything!).

G.

[Iron Clad]

Thanks DKunkler. Neat book. I just read most of it on PDF. I would like to own this one. Looks like with this book a person can put a blacksmith and wood shop together, build a house, make furniture, and tell time. All it needs is a section on growing food and making cloths and your all set!

The best thing about this book is learning how it was done back then. I like the section on the foot powered wood lathe also.

[ThomasPowers]

Moxon is definitely a window on another time and one of the "key" books if you are working on the history of the craft.

[Sam Thompson]

Given the difficulty of making these things accurately by forging and the evenness of the original piece, I think it likely that the originals were cut out. This kind of thing was pretty much mass-produced in small factories and they would have used the simplest method available. The waste produced would have been easily large enough to use for other components.