The Bucket Foundry

[WilDun]

To be honest, it wasn't all plain sailing, drum brakes, anyone remember them? owners
But aren't they buggers of things (drum brakes) not much wear in the shoe and the actuator cam starts to overcenter, and jam up.

Yes discs are a great leap forward!
I would put it all down to brake fade rather than shoe wear, where (as in a long downhill stretch), the drum would heat and expand big time and the tension on the spokes wouldn't help, this I found out after just one lap of Pukekohe on my old T20 Suzuki (getting well over 40 years ago) - 45YEARS!

Your remedy did work though!

[husaberg]

To be honest, it wasn't all plain sailing, drum brakes, anyone remember them? Half way round on the first circuit the engine started to labour after a long down hill, thought shit it's going to seize but as I pulled the clutch engine freed up and the bike stopped suddenly. Rear brake was jammed on! Kicked the leaver on the drum and we were away again, no more rear brake for the rest of that circuit. Luckily the full service workshop tool kit I take had enough spares to repair it for the next long loop. Mandatory for all Kawasaki owners
But aren't they buggers of things (drum brakes) not much wear in the shoe and the actuator cam starts to overcenter, and jam up. In the old days I used to fit a sleeve over this cam to make it bigger for use with worn shoes so as to get the most usage out of the shoes. Might have to go there again! Aren't discs a giant leap forward. I guess I shouldn't grizzle as I see the hour meter is just on 70 hours now.

Neil you need to find a 1981-82 YZ250 drum brake or brakeplate they were a nice little 2ls, not to fierce either.
Similar years Honda XL250 and 500 also had a nice little 2ls

[Flettner]

Neil you need to find a 1981-82 YZ250 drum brake or brakeplate they were a nice little 2ls, not to fierce either.
Similar years Honda XL250 and 500 also had a nice little 2ls

O no, that wouldn't be original
Old Kawasaki brakes weren't / aren't all that bad, just the maintenance, as with any drum brake!

[Ocean1]

Similar years Honda XL250 and 500 also had a nice little 2ls

They weren't much better, I've had to do Neil's trick on at least two of them.

[Grumph]

O no, that wouldn't be original
Old Kawasaki brakes weren't / aren't all that bad, just the maintenance, as with any drum brake!

You very obviously never owned a drum brake Mach 3....They WERE that bad.

I'm watching your trail riding anxiously in the fervent hope you won't hurt yourself before the 24th....Please.

[husaberg]

O no, that wouldn't be original
Old Kawasaki brakes weren't / aren't all that bad, just the maintenance, as with any drum brake!

oh hush now, I am pretty sure most Yamaha framed, fuel injected, f9 bighorns came out that way.

They weren't much better, I've had to do Neil's trick on at least two of them.

I used to use newspaper printing aluminium sheets.
They are shimirific. Plus you can cut them with scissors.

[Ocean1]

I used to use newspaper printing aluminium sheets.
They are shimirific. Plus you can cut them with scissors.

I found the shoes wore first, I'd make wee stainless packers that clipped on. And bush the shafts. And hard face the cams... :

[husaberg]

I found the shoes wore first, I'd make wee stainless packers that clipped on. And bush the shafts. And hard face the cams... :

Clipped on?

[Ocean1]

Clipped on?

See pic, where the alloy shoes had a steel pad cast into them where the cam contacted? It's rounded at the edges, into what looks like a slot.

I'd make a 16swg packer and roll the upper and lower edges around the edges and into those slots so they stayed put.

[husaberg]

See pic, where the alloy shoes had a steel pad cast into them where the cam contacted? It's rounded at the edges, into what looks like a slot.

I'd make a 16swg packer and roll the upper and lower edges around the edges and into those slots so they stayed put.

Engineers aye

Cut strip of thin alloy sheet and wrap around cam, then stuff in shoe. have a beer Sorted
actually drink beer and then use empty beer can for shim.
oh i forgot, then move lever around on spline, but not too much.

[Michael Moore]

I got a fair ways on the milling operations for the upper head pattern before catastrophe hit.

It seems I found the limit of the wax fins to take a side loading as when I was at the level shown in the second photo and started the operation to trim the ends of the fins two of the short fins snapped off. I reposted with slower feeds and changed control parameters for slower acceleration rates on the axis motors and immediately snapped off two more of the short fins.





I'll need to melt this and all the swarf down and make a new block. I was hoping I'd be able to finish the rest of the part and then cast two 55% width sections in urethane and then trim them down and glue them together on the center line for the working pattern, but that doesn't look likely now.

I think it will be pretty straight forward to reorder the existing operations so all the pocketing and end trimming is done first, and then all the cuts to separate the parallel fins.

I wasted my time drilling the extra cross holes higher than the bottom two which I still think will be useful when the taper ball mill gets in that area, but I learned that they weren't needed so now I know. I'm keeping notes as I watch the mill work so I can improve future operations.

I think I'll still come out ahead over trying to piece together a wooden pattern. Renshape would be stronger than the wax, but if I'd found a similar "oops" point with it the rest would be scrap instead of heading for the melting pot. Of course, if I continue to find the wax a bit weak (it worked fine on the much shorter fins on the lower surface pattern) I can always switch to a different material.

cheers,
Michael

[Grumph]

Impressive - and very handy being able to remelt the swarf too.
Going to do any hand finishing ? Radius fin ends etc ?

[Michael Moore]

The Webco head is pretty flat on the outer ends as shown in the second photo, and the tops and inner ends of the fins are radiused. I did a parallel finishing op after the first photo to form the tops of the fins and the inner and outer top corner radii. It was an inner corner/vertical radius that was being done when the fins snapped.

The plan is to do no more hand work than slightly rounding the vertical edges on the outside ends, just enough to break the edge.

If you zoom in on the perspective view of



you can see how the inside upper corners are radiused all the way but the front/rear edges are basically a surface that rolls up over the corner. Here's a photo of a head that shows the flat fronts of the fins:



I'll give the wax one more try, but I'm also going to call and talk to Freeman's tech support about the Renshape foundry boards.

cheers,
Michael

[Grumph]

Looks like the Webco casting has been rolled over a linisher to finish the fin edges.

I've restored a couple of RD350's and post painting the heads and barrels that's how you get the factory clean fin edges...

[swarfie]

Engineers aye

Cut strip of thin alloy sheet and wrap around cam, then stuff in shoe. have a beer Sorted
actually drink beer and then use empty beer can for shim.
oh i forgot, then move lever around on spline, but not too much.

On my drum braked dirt bikes, to get more wear out of the shoes I used to make up a removable/bolt in pivot pin (the pin the shoes rest on at the opposite end to the cam). I'd then turn up different thickness rollers to fit over the pin and file a larger radius in the shoe to suit. That way the shoes wouldn't get less contact patch as they wore but more and the brakes stayed more or less constant as they wore down (well as much as drum brakes could anyway) and I'd be able to get heaps more life out of them. Give that a go Neil and you'll be able to dig all your old shoes out and use them until they're really rooted