Myford Super 7 Belt and change gear cover material

Does anyone know what the material that belt and change gear covers on a Super 7 are cast out of.

Is it Aluminium or is it Zinc based material such as Zamak?

Has anyone tried welding the covers and was it successful.

My change gear back cover has a large crack in it from 60 years of use in hte hinge area and I am looking at repair options. The 2 options I have are

1. weld the crack..

2. Use JB Weld to glue and screw an aluminium cover plate secured by a combination of JB Weld and screws over the top to make a laminated joint.

Thanks

Peter

Mine had a broken hinge on the clutch cover and I was able to solder it back together with "Lumiweld," not the most cosmetically pleasing job I've ever done, but it has remained mechanically strong and a bit of JB weld type filler followed by some grinding off of the excess with a mini-grinder made it look okay. I'd put my guess on it being an aluminium based alloy.

When I bought my S7 this casting was cracked at the hinge. I took it to a mate that repaired aluminium former for the shoe trade.He welded it with a stick welder (DC?),That was 25+ years ago and is still good.

I'm almost certain that it's not Zamak ... A rough measurement of the density [*] should confirm: **LINK**

https://www.dynacast.com/zamak-3

MichaelG.

.

[*] which is more than double that of Aluminium

Edited By Michael Gilligan on 18/10/2018 08:56:34

Peter

When I refurbished my S7 over 20 years ago I discovered a crack in the area you mention. Not wanting to risk welding, I used your option 2 approach, though I used Araldite not JB Weld. The repair is still solid as a rock.

I repaired and modified my Super 7 change gear cover using the stuff the Scandiwegian chap sells at the ME shows. I welded the hinge section back on and replaced some bits I couldn't find

Above is a bit of Aluminium plate cut to fill in for a missing section, below is it welded in place. 

I also cut out the standard tubular section and welded in a section of turned Aluminium tube to allow a suitable big bore rear extension to clear the cover when opening & closing

The welds are very strong, I bought another 6m of the wire at the show after I did this repair.

Edited By Nick Hulme on 18/10/2018 09:35:16

Edited By Nick Hulme on 18/10/2018 09:36:55

Like Nick above I have repaired a Myford cover using "Alutight" (the stuff the Scandi chap sells at shows). Very satisfactory and easy to use. However I found that the cover material is very easy to melt if you get a bit heavy handed with the torch. Then you have to build up the hole with more Alutight

no picture as I no longer have that machine.

Funnily enough it was also a change gear cover that I repaired - they don't like heavy chucks falling on them from the shelf above the machine!

Edited By Robbo on 18/10/2018 18:34:29

I will try welding next week. A local welding supplier has a teflon liner and a small roll of aluminium mig wire. Will be down that way on Tuesday.

Will Mig weld the crack.

Peter

Yes, if, like me, you have a bottle of Argon to go with it.
I have TIG too but I know that cast parts can vary from interesting to a right bugger to weld with any electric system depending on the alloy and casting quality so I used something I knew would work perfectly regardless of the alloy or quality of casting,

HTH,

Nick

Hi. I repaired mine 15 years ago. A piece of 1/2 x 3 strip was bent approximately to shape (hot) , drilled and the cover was tapped M5 for screws The strip was bonded down with Araldite. No need to get it hot by soldering messes up the paint! It has been completely successful.

for some reason the photo is upside down despite rotating it and reloading

From the inside the crack can still be seen

Is it done yet?

Do we get pictures?

I have the teflon liner fro the MIG torch, .9mm 5356 Aluminium MIG wire and oversize tips for .9mm.

Just need to get some time over the weekend, but I will photograph.

Have been cleaning the aluminium in preparation to weld. The intention is to tack it first then fill in the gaps between the tacks. I have been advised to preheat the casting first.

Peter

The belt guard you need. Is it the pear-drop shaped one with long slots in it? I have one of those off a ML7, if it will fit.

The actual part that broke is the backplate for the change gear cover on a 1958 Super 7B. It had a crack in the hinge area which had a piece of steel attached by 2 screws to reinforce the area where there was a crack when I acquired the lathe almost 30 years ago.

Was putting the lathe back together after a bed grind and some other work when it broke through. I was rushing as the lathe was in pieces and we are moving house soon, needed to be back together for the move of about 1800Km sometime in the next few months.

Peter