Diecast on old machinery

**electrosteam** · 7th August 2010, 12:07 AM

I have already identified a failed diecasting on my Kondia mill in the thread "Bridgeport Clone Ram Clamp" ( I will sort out how to do active links 'soon').

That first failure on an old mill is not really a problem as that feature was dropped on later built units, and I will easily duplicate it in steel later.

Now, however, I have a failed diecasting in something important, the fine feed selector lever.

The attached photo shows fine cracks along some edges in the diescasting (ignore the impact damage).
I removed the plate and found the shaft or selector handle frozen solid to the diecasting.
The handle can be moved by applying force (in vyce on bench).
I conclude that the diecasting has grown or moved to take up all the operating clearances, making the selector stiff, very stiff.
Cracks can be observed internally.
The internal fine feed mechanisms are in good shape and work fine.

Unfortunately, the feed selector must be in the highest rate to install the plate, so I am stuck with 0.120 mm/rev feed until I make a new plate.

I have checked the mill for other diecastings, but none found so far.

If you buy old machinery, check the diecastings !

Happy machining,
John.

**Greg Q** · 8th August 2010, 09:59 AM

John...I can't quite make out the defective part. Is it the plate or the handle?

If the handle I have had good luck using Alesa handles (German company-their dealer here is North East Industrial in Heidelberg)

Greg

**electrosteam** · 8th August 2010, 04:47 PM

Greg,
If you look closely at the photo, you will see fine cracks along the edges where the various flat surfaces, horizontal, sloped and vertical, meet.

It does initially remind one of paint cracking on the bend, or of dirt streaks, but they really are cracks.
It is typical of diecasting to swell dimensionally as it deteriorates, destroying the original shape.

The shaft connects to a disc with a pin in it that moves a floating guide vertically on a shaft held by internal protrusions in the diecasting.
The floating guide engages a 3-way cluster gear that engages gears driven from the spindle by a dog-ctutch and worm gear.
The vertical shaft was removed as part of the investigation.

The tightness reported is either the shaft operating in the bearing hole that has closed up, or more likely, the flat diecasting between the handle and disc has grown adding excessive friction.

A replacement will be made on the mill once it is operational.

John.

**antoni** · 9th August 2010, 12:18 AM

Hi could you made one up out of block of aluminun ?
whats it look like on the in side.
If it is die cast can not weld.
Tony

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