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Dog Clutch tooth shape

Are dog clutch teeth supposed usually to have 90 degree flanks, or are they sometimes inclined like an acme thread?

I have a power guillotine (4 foot x 1.6mm cut) that spins a flywheel with a

1.1kw motor, and pressing the treadle allows a dog clutch to engage via spring pressure rotating eccentrics which pull the upper blade through the material. Recently under full width cuts the clutch has taken to not fully engaging, and jumping out of engagement. The flanks are obviously fairly worn and need re-machining, but what shape to make them - they could have been inclined or this could be the wear with them starting off perpendicular - any suggestions?

AWEM

Reply to
Andrew Mawson
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Gearbox dogs are usually cut slightly the other way (undercut), and they have no problem engaging/disngaging even under a bit of a load.

Reply to
Pete

If there is any possibility that they need to engage while moving relative to each other, they either need a bit of an inclined flank or a lot of clearance to lessen the likelihood of fractional engagement and damage to the corners of the teeth. Springs will help the clutch to stay engaged against the pressure from the inclined teeth.

How's about the form used by Bridgeport clutches as a first approximation?

Regards Mark Rand RTFM

Reply to
Mark Rand

A big spring pushes them into engagement, a foot operated peg bears on an axial cam profile to pull them apart - this same peg eventually falls into a hole that stops the rotation after one revolution. They will always have relative rotation until engaged as the flywheel is spinning and the shaft holding the eccentrics is stationary until the clutch engages with a frightening whack! Are you meaning the Bridgeport back gear dog clutch? Trouble is the bits are pretty massive, and removal is no five minute task! I'm tempted to go at them with an angle grinder in situ!

AWEM

Reply to
Andrew Mawson

Yes, the back gear clutch was what I was thinking of (not that I've got one, since I've got a Beaver :).

Possibly, start with the angle grinder and finish with the die grinder and some blue to try to get reasonably equal engagement on the teeth?

When do you get to the point of competing directly with Tata/BSC Port Talbot+ Llanwern? :-)

Regards Mark Rand RTFM

Reply to
Mark Rand

Now why doesn`t that surprise me?

More like E.M.R.

Reply to
mark

It's only a modest little guillotine !

AWEM

Reply to
Andrew Mawson

Normally 5 to 7 degrees undercut, and nothing wrong with the angle grinder approach.

John S.

Reply to
John S

You can also use hard welding rods to build up the worn edges prior to using the angle grinder. The advantage being that you then only have a small amount of metal to remove and it avoids disturbing the overall profile and sizes.

Used that on an old geared head drill's dog clutches (scrapyard) many years ago and it still works...

Regards,

Chris

Reply to
ChrisQ

Of course, another answer might be that the thing is out of adjustment, in that with full width cuts, the clutch may still be iengaging when the load appears ?...

Regards,

Chris

Reply to
ChrisQ

"ChrisQ" wrote

I rebuilt the edge of a wood splitting maul, which my uncle had used to trim a granite porch step, with snowplow hard surfacing rod . The new end was easy enough to grind sharp and has held up well, though it hits only oak now.

Beating an axe to death against a rock was greatly preferable to ignoring my grandmother's request.

jsw

Reply to
Jim Wilkins

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