They look like locks to me.
Mine are outboard and clamp down in a groove around the perimeter of the top. Very solid.
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Looking for a Lathe Face Plate and a Lathe Dog Drive Plate
- Thread starter YYCHM
- Start date
They look like locks to me.
Mine are outboard and clamp down in a groove around the perimeter of the top. Very solid.
I haven't known many RT's so I cant say. Some people say to leave the clamps on with very light pressure when doing heavy or interrupted or climb rotational cutting to try & avoid kick back from the end mill with a loose-ish table. But I don't know if that means a worn RT or just general machining. I can't image that partial clamping action would be a 'feature'. Hopefully they are worn & no longer gripping or out of adjustment & you can get a lock out of the deal. But do some YouTubing on RT disassembly & ideally parts schematic for your RT model. Some of them have a specific sequence of dismantling, some surprise set screws holding collars, press fit here, slip fit there....
Here is what I think is happening:
As your contact pad wears on the brake shoe, the angle of the shoe needs to change to compensate. If the brake adjust screw hole is too tight, it can’t pivot to allow the change in angle. So no matter how much you tighten the screw, the pad will not move in to make contact with the rotating table flange.
The adjusting screw actually needs a bigger through hole through the base and a hemispherical washer on the outside to allow the shoe enough movement to make contact and act as a brake.
Here is what I think your brake system looks like (base on the photos you show). I have never actually seen a RT like yours in person, so guessing...
Yes, there are times when I “drag” the brake on the RT while milling. It must be done with fine feel as a little goes a long way (my BP RT has a very powerful brake/lock).
As your contact pad wears on the brake shoe, the angle of the shoe needs to change to compensate. If the brake adjust screw hole is too tight, it can’t pivot to allow the change in angle. So no matter how much you tighten the screw, the pad will not move in to make contact with the rotating table flange.
The adjusting screw actually needs a bigger through hole through the base and a hemispherical washer on the outside to allow the shoe enough movement to make contact and act as a brake.
Here is what I think your brake system looks like (base on the photos you show). I have never actually seen a RT like yours in person, so guessing...
Yes, there are times when I “drag” the brake on the RT while milling. It must be done with fine feel as a little goes a long way (my BP RT has a very powerful brake/lock).
That's what it looks like alright. There are two of them. Both were screwed down as hard as I could make them without resorting to a vise grip on the screw driver. Still you could rotate using the crank with out much effort but never lock per say.
The other thing that could be a factor is wear on the surface of the brake shoe
If the screws were tight'ish at some point and the table was rotated, metal would have wore off the face of the brake shoe. Rinse and repeat and there's the potential as @RobinHood points out that there isn't enough play left for the brake shoe to make adewuate contact with the table to stop rotation.
If the screws were tight'ish at some point and the table was rotated, metal would have wore off the face of the brake shoe. Rinse and repeat and there's the potential as @RobinHood points out that there isn't enough play left for the brake shoe to make adewuate contact with the table to stop rotation.
Pheeew…. 832 end mill passes and 32 drilling operations later...….
Oh ya.... and 4 trips around the world on the RT. The front needs some deburring.
And the back side. Recessed for 3/8" hex head bolts and nuts. Only two s...w ups. One of the back slots is over size a smidge. Ends up my ER20 13mm collet is toast from my taper attachment shoe crash and exhibits excessive runout. The other was when my RT decided to go walk about but that's just a minor cosmetic detail.
And as a bonus I never once drilled into or milled the table of my RT
That's mind boggling unto itself.
@David_R8 the pressure is on now..... I'm looking forward to your slotting exploits.
Oh ya.... and 4 trips around the world on the RT. The front needs some deburring.
And the back side. Recessed for 3/8" hex head bolts and nuts. Only two s...w ups. One of the back slots is over size a smidge. Ends up my ER20 13mm collet is toast from my taper attachment shoe crash and exhibits excessive runout. The other was when my RT decided to go walk about but that's just a minor cosmetic detail.
And as a bonus I never once drilled into or milled the table of my RT
That's mind boggling unto itself.@David_R8 the pressure is on now..... I'm looking forward to your slotting exploits.
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Brent H
Ultra Member
Excellent!!!! Well done @YYCHobbyMachinist
My 0.005 DOC was me being paranoid about disturbing the setup. I'm not following the 3/8 vs 1/2 thing here? That's quite the discrepancy?
This is one of the brake shoes (clamps?)....
Some one has greased the slot the shoe fits into on the rotating table?
The screw is a very loose fit in the through hole and a fine thread. The fact that it's knurled would suggest it's not meant to be cranked down hard?
Not sure what could be done to improve it?
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The narrow one. The wide one is stationary.