Help me diagnose

holsgo · Post by **holsgo** » Sat Aug 13, 2011 9:48 am

I was spinning a 3/4 bit into 3/8 alum.
Speed was low but out of the jig saw range.
Louder than normal screech from drive sheeve assembly I think but cover wasn't off.
Gilmer, 1954.
Happened as I plunged into the metal.
Running too slow perhaps or you think I've got to do the bearings? I'll pull the cover in about an hour when I get back and dig in.
Thoughts?

JPG · Post by **JPG** » Sat Aug 13, 2011 11:11 am

holsgo wrote:I was spinning a 3/4 bit into 3/8 alum.
Speed was low but out of the jig saw range.
Louder than normal screech from drive sheeve assembly I think but cover wasn't off.
Gilmer, 1954.
Happened as I plunged into the metal.
Running too slow perhaps or you think I've got to do the bearings? I'll pull the cover in about an hour when I get back and dig in.
Thoughts?

IMHO the ss does not run slow enough to drill 3/4" through aluminum. I assume you were using a twist drill.

Question is, does it still deliver normal torque to the quill shaft.

Hopefully the screeching was the slip clutch performing its intended duty.

holsgo · Post by **holsgo** » Sat Aug 13, 2011 11:42 am

I had used a series of drills up to the 3/4 so it wasn't drilling that size straight away. It just seems that the torque is fine, just a screaming as the 3/4 was plunged into the material. It still runs through all of the speeds, no known slippage or screaming otherwise. You are probably right about the speed. I can only assume the clutch was working as intended.

JPG · Post by **JPG** » Sat Aug 13, 2011 11:51 am

holsgo wrote:I had used a series of drills up to the 3/4 so it wasn't drilling that size straight away. It just seems that the torque is fine, just a screaming as the 3/4 was plunged into the material. It still runs through all of the speeds, no known slippage or screaming otherwise. You are probably right about the speed. I can only assume the clutch was working as intended.

Don't 'plunge'! Advance 'slowly'!:D

holsgo · Post by **holsgo** » Sat Aug 13, 2011 12:22 pm

It was odd. I did a slow advance and that's when the problem started. Its either I had a dull drill, which I'm going to regrind or too slow or too fast. Must have been too fast and a dull drill at didn't allow the bit to penetrate. Hadn't heard the machine slip like that before.

JPG · Post by **JPG** » Sat Aug 13, 2011 12:37 pm

holsgo wrote:It was odd. I did a slow advance and that's when the problem started. Its either I had a dull drill, which I'm going to regrind or too slow or too fast. Must have been too fast and a dull drill at didn't allow the bit to penetrate. Hadn't heard the machine slip like that before.

Sure it did not grab just enough to 'stall' it out?

What size hole was the bit being feed into?

holsgo · Post by **holsgo** » Sat Aug 13, 2011 1:21 pm

It was a sequence of holes drilled from 1/16 to finally 41/64. The last bit was obviously the 41/64 and it was drilling after a another bit, just a few sizes smaller. So it was only removing a bit of metal. That what makes me think the bit was dull and grabbing. Either way, the sound threw me off and made me believe I had a weekend of tearing apart the machine ahead of me.

drl · Post by **drl** » Sat Aug 13, 2011 3:29 pm

Possible jacobs chuck was not tight enough to hold the drill bit and the bit spun in the chuck? Just a though.
Regards,
Dwight

JPG · Post by **JPG** » Sat Aug 13, 2011 3:36 pm

drl wrote:Possible jacobs chuck was not tight enough to hold the drill bit and the bit spun in the chuck? Just a though.
Regards,
Dwight

Speaking of which, we do all know to tighten using all three holes twice around!!!:)

holsgo · Post by **holsgo** » Sat Aug 13, 2011 5:03 pm

Luckily I have 2 SS in my garage right now so I've been able to compare a bit. The other SS behaves the same way as mine so I think, and hopefully I'm right (or JPG is) that the clutch slipped. Now, I have a very early greenie so I do hope it does indeed have a clutch. But, I think I simply pushed the bit too fast, wrong speed. After doing the same hole in the same order with a hand drill it was quickly apparent that the bit does bind. So, I'm sure it bound in the hole while using the SS. Just freaked out to hear the machine crying unckle. Then again, I'm always doing something to test this things limits.