Need to fix an eff up, can I fill a hole in cast iron with silicon bronze?

Flyinfool said:
There will not be a lot of force on that plate in use. Since you need a very long drill to get past the chip pan, you definitely need to make up a drill guide plate. That is about the only way you will get the holes in the correct position and straight.
As for the holes you already have. Can you make the slots longer and then move both holes toward the center of the mounting plate by about a half inch or so, so that they miss the bad holes and you still have full adjustment range. Clean out the bad holes real good and fill them with JB Weld, no one will ever see them behind the stepper mounting plate.
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The drill guide plate, what does this look like? How would it attached to my plate?

Think that I can extend the slots a bit and plug the drill holes. But I need a good way to fix the drill guide to the plate and or lathe.
 
WobblyHand said:
The drill guide plate, what does this look like? How would it attached to my plate?

Think that I can extend the slots a bit and plug the drill holes. But I need a good way to fix the drill guide to the plate and or lathe.
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Make up a plate with four holes rather than slots. Use the two existing tapped holes to mount the plate. This will provide a positive location for starting the holes. I actually prefer a longer drill for free hand drilling as is provides me with a better visual of drill alignment. For vertical alignment, a small bubble level works. For horizontal alignment, I visually check for square. If I can't use a level, once I start the hole. I will bend over and visually check for squareness.

If you decide to make a drill guide, You can turn a couple of bosses and weld them to your pattern plate and drill them for your 5mm holes. That will give you a longer guide without needing a thick plate.
 
A drill guide is simply a plate with a drilled and reamed hole that the tap drill just fits through. They normally use hardened bushings but for a one off it won't matter. Hold it on the lathe with clamps and whatever will hold it there
 
benmychree said:
One issue that has not been brought up is the likelyhood of cracking of the cast iron from concentrated high heat, a distinct possibility, better to explore other options, perhaps a steel plate sub base for the motor held onto the cabinet with flat head screws and tapped for the motor base???
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This sounds like it might be the best option. You might have to mill the original mounting plate a little thinner to keep the belt inline.
 
Just for fun said:
This sounds like it might be the best option. You might have to mill the original mounting plate a little thinner to keep the belt inline.
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The mounting plate spaces the pulley due to its design. The motor is recessed into the plate by about 14mm to align the pulleys. Designed that part in FreeCAD to get everything to line up. Made a partial model of the lathe to get all the spacings.
PXL_20220903_125728022.jpg
 
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Lo-Fi said:
Careful with the TIG on cast iron, it's not hard to get it to cook up the carbon and make an epic hard spot.
Also be careful to buy bronze rods specifically for TIG or you'll have a really bad day in the shop.
The alternative is to drill a bigger hole, thread, plug and re-drill if you have space. Call it an offset helicoil. If the cast is pretty clean and not lived it's life submerged in oil, you might get away with an epoxy putty repair similarly.
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Epic hard spot will ruin your day!
 
Do not attempt to weld, the heat will ruin the paint and may cause warpage.

Make threaded plugs from whatever you have handy, do not worry about the breakthrough, just make them so the surface can be flush.

Unce your fit is good use GOOD epoxy to finish.

You can cut a slot to allow driving in with screwdriver then either leave tall and file flat or fill slot with epoxy.

Once cured you can then make smooth the surface and then do again.

Paint with final paint or ink it up.

Make a plate that matches what needs to go here.

Drill 1/8 inch holes exactly where they need to go.

This is your drill guide.

Long 1/8 drill bits are cheap and can flex a lot.

Clamp the plate in place then with the long drill that can flex just Peck the holes to leave marks, remove plate and inspect.

Check alignment and if good put plate back on and drill holes.

Remove plate and enlarge holes to final size in plate.

Reattach plate and drill again.

Tap holes and done

Sent from my SM-G781V using Tapatalk
 
There are many brazing rods out there that can be used with a normal torch...I'd go that route. I have used the Ble Demon triple play. To tig that you'd have to preheat the hell out of it....sounds like a lot of issues to me. I feel your pain, been in similar situation more than once!
 
Even with a new mounting plate there is still the issue of needing a drill guide to drill straight holes in the correct places in the casting of the lathe.
 
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