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Repairing a SDS rotary hammer drill, how much torque on the friction slip clutch nut?

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My rotary hammer stopped rotating and was only hammering.
I found the nut had backed off that hold the friction clutch together, so the bits no longer rotated.
The nut is left hand thread.
I was wondering how tight that nut should be.
This is a CMT drill I got from Ebay many years ago

I am thinking just use my air wrench on the nut to tighten it up while letting the gear spin.
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I also had to repair and then shim the selector arm pivot that engages-disengages the hammer action.
Spring pressure wore it down. The design means spring pressure is always on that. Right gear has this sliding rod that disengages the hammer action, that rod cylinder bears down on the lever arm constantly
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I totally took everything apart to clean it and was surprised how much gritty stuff gets into it. I suppose from beating on concrete and bricks.
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Discussion Starter · #3 ·
The motor and gears are back together and they run good.
I cleaned the hammer sds tip.
Will have it back together in a few days. Got a busy weekend coming up.

I used the air wrench and spun the nut on tight enough I think
I did not want to clamp the bevel drive gear or the other gears, could damage them

Might could use a piece of wood to jam the gears and tighten the nut
 

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Discussion Starter · #4 ·
Found the time to put it all together. It is fully working, video

I had to make a tool to compress the rotary driven gear that fits on the hammer cylinder as there is a very strong spring has to be compressed to get to the round ring that holds that gear on.
The perfect removal tool uses this and a large cartridge caulk gun. The entire front piston assembly fit into the gun and I was able to compress the gear down.

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And the nose on this one, simply unscrew the metal collar nut and you can take the front off to clean it, the locking mechanism for the SDS bits.

There are 3 air hammer pistons in this rotary hammer.
I used 3 different oils
Mystk grease with a high moly content for all the gears, bearings. (Oreilleys sells)
5w-50 for the pistons
Some gear oil to lube a few metal shielded ball bearings

This rotary hammer has a variable speed, it has not gotten much use but works very well, until the nut on the clutch backed off and it no longer spun.
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Found the time to put it all together. It is fully working, video

I had to make a tool to compress the rotary driven gear that fits on the hammer cylinder as there is a very strong spring has to be compressed to get to the round ring that holds that gear on.
The perfect removal tool uses this and a large cartridge caulk gun. The entire front piston assembly fit into the gun and I was able to compress the gear down.

View attachment 722282

And the nose on this one, simply unscrew the metal collar nut and you can take the front off to clean it, the locking mechanism for the SDS bits.

There are 3 air hammer pistons in this rotary hammer.
I used 3 different oils
Mystk grease with a high moly content for all the gears, bearings. (Oreilleys sells)
5w-50 for the pistons
Some gear oil to lube a few metal shielded ball bearings

This rotary hammer has a variable speed, it has not gotten much use but works very well, until the nut on the clutch backed off and it no longer spun.
View attachment 722284
And all done on the dinning room table....are you still married?
 
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