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View Full Version : Plywood work holding jig for the mill.



bob ward
03-22-2011, 09:00 AM
This is a little job I did for myself recently.

A while ago I had a sheetmetal shop make up this stainless 9" x 27" fuel tank, its going in a '48 Morris 8 Series E tourer. I provided the shop with the machined, drilled and tapped flange for the fuel gauge sender, which they welded in while making the tank. Fast forward 5 years or so I fit the tank to the car, fill it with petrol and the f'in thing leaks badly, it turns out the flange distorted during the tigging and has a 1mm .040" bow.

http://i237.photobucket.com/albums/ff28/sirrobertthegood/IMG_0041-1.jpg

I thought about filing the flange flat, which wouldn't have been perfect but which probably would have worked, but then again if I can get the tank in the mill, I can get the flange dead flat. So its 30 minutes filing versus a few hours making jigs. Hmmm.. No contest, I'll make the jigs.

Fortunately I had offcuts of 15mm .59" flooring ply I could use, so using a 6mm router in the mill at its max 2400RPM I made these nice accurate ply squares and rectangles with a 9" hole.
http://i237.photobucket.com/albums/ff28/sirrobertthegood/plycircles.jpg

Epoxy the circles together then cut them, to make 4 saddles 45mm 2.75" wide. The grooves are for the hold down bolts.
http://i237.photobucket.com/albums/ff28/sirrobertthegood/IMG_0030_3.jpg

This the set up just prior to milling, the saddles are held down with 12mm bolts and there are pipe tube spacers holding the saddles together fore and aft. Note the folded paper packers in keeping with the ply theme.
http://i237.photobucket.com/albums/ff28/sirrobertthegood/IMG_0031-2.jpg

After all this, the machining itself was a minor job. New cutter, light cuts and all done, the jig worked a treat. And no more leaks.

davidh
03-22-2011, 09:13 AM
how about a pix of the morris. ?

Forrest Addy
03-22-2011, 09:36 AM
Way to go. I've even used plywood "parallels, "saddles as you have shown, brackets and angle plates, stops, hell, the list goes on. So long as long term accuracy where humidity is a problem, ultimate rigidity, closer than 0.005 accuracy etc is not a problem wood works very well on a machine tool set-up..

Dr Stan
03-22-2011, 10:36 AM
Plywood, and on occasion MDF, works well for fixtures including welding fixtures. The first time I saw it being used as fixture material was at an outdoor furniture plant for welding jigs for aluminum chairs.

Well done.

I too would like to see pics of the Morris. :D

Mr Fixit
03-22-2011, 09:00 PM
I am a Morris fan here in the states. Just going to share this link for the heck of it I'm sure Bob will post real pic's when he can.
http://www.vintagecarportraits.co.uk/pages/Morris8Etourer.html

Chris :)
Mr. Fixit in the family

Black_Moons
03-22-2011, 09:29 PM
Nice jig! Next time do what I did. Wait 4 weeks for ebay postage, spend $80 on 2oz of silver solder because you want two diffrent types without even knowing the diff beween em, And then silver braze it on :) Worked like a charm. 100% seal and the job looks totaly pro, Except for the tiny, tiny little 'droplet' where I used the tinyest bit too much silver.

Seriously, silver solder flows sooo nice, Especialy the 56%.

bob ward
03-24-2011, 06:30 AM
Its getting there. Imported chassis and front clip, bodied in Australia by Richards.

And to shamelessly promote an unusual car I have on ebay at the moment.
http://cgi.ebay.com.au/1948-Alvis-TB14-Sports-/220758005847?pt=AU_Cars&hash=item336633d857#ht_500wt_1123

http://i237.photobucket.com/albums/ff28/sirrobertthegood/IMG_0029-3.jpg

http://i237.photobucket.com/albums/ff28/sirrobertthegood/IMG_0030-3.jpg

http://i237.photobucket.com/albums/ff28/sirrobertthegood/IMG_0036-1.jpg

rockrat
03-24-2011, 09:55 AM
As the op shows, nothing wrong with using plywood. I have also used it many times before. Its cheap, handy, always laying around, I dont feel bad about tossing it when I'm done and it is not nearly as heavy as steel of the same dimensions.

Good setup Bob, "tanks" for sharing. :D

rock~

lynnl
03-24-2011, 02:53 PM
Fortunately I had offcuts of 15mm .59" flooring ply I could use, so using a 6mm router in the mill at its max 2400RPM I made these nice accurate ply squares and rectangles with a 9" hole.
http://i237.photobucket.com/albums/ff28/sirrobertthegood/plycircles.jpg



Clever!

How did you do the circles? ...use a rotary table? Or drill a pivot hole in each?

bob ward
03-24-2011, 08:57 PM
lynnl, I used a rotary table with ply packers between the rotary and the circles. I milled/routered each circle and rectangle in one set up, ensuring the saddles would be all the same height.

SGW
03-24-2011, 10:00 PM
Strictly speaking, aren't they fixtures, not jigs? I've always understood that one has holding fixtures and drilling jigs.

Regardless, it's nice work!