Broken Tips Colchester

Machine Shop
#1

Nick et al.

I was using the Colchester today, and broke two tips. I turned them around, so that they are still usable, but I thought I’d let someone know. I’m not exactly positive what the difference is between the silver tips and the brass colored ones. I did find a few tips in the cabinet, but did not feel comfortable replacing without knowing the difference.

Also, the three jaw chuck was significantly off, and I unmounted it. It will likely need each of the jaws removed and reset. The 4 jaw is in place right now. Nick wanted me to send a note to remind him.

Lastly, I managed the break a cutoff bit as well. I put it in the broken bits bin. I will pay for any parts that I need to replace. I’m not sure how I managed to break this one. I ran a slow cut straight in to the middle. There was plenty of fluid. It just sheared.

Lastly the lathe was bone dry on cutting fluid, so I put some of the premixed fluid from under the drill press.

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#2

Thanks for letting us know, the inserts do wear and break and are made to be rotated.

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#3

The brass colored ones are for steel & harder metals. The silver colored ones are for non-ferrous metals.

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#4

I was passing thru on the way to my HAAS class. One of the 3 jaws is definately tilted and would not hold a workpiece. It may simply need to be backed out all the way and then reseated. I won’t have time to do it tonight.

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#5

3 jaw is out of commission. Will have to have a new set of master jaws. Jaw number 1 is done.

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#6

Thank you. Can I add that to the class materials. I went back and looked through the ppt before operating again, and could not find that information.

#7

Hmmm. Is this something that I managed to do, or is this wear over time? If I need to pay for something please let me know. I was turning a piece of 2" steel, and at some point, the bit caught and knocked the piece off balance. I’m not sure if the jaws were already not holding well, and that is what caused it to be displaced, or if I did something stupid. I don’t feel like I did, and I was running at pretty low speeds < 120 ft/s per the specs.

#8

IMO this is a cumulative fatigue failure. You just drew the lucky straw to break its back. To do this in “one event” I would expect pretty heavy damage to the tool post/insert holder.

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#9

It had been getting more bell mouthed over time, as the jaws were not as parallel anymore it made it more likely it would lose grip on a part, I noted it last month here Rogue Strandbeest Mk2 Build

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#10

Speaking to my work mate, he suggested there is the possibility it bent the spindle shaft and could have cracked a gear. On the first if it is tapering when not expected is a clue and we can visually just check the gears

#11

We can check the runout on the spindle pretty easily as well as any bearing slop.

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#12

Good news is the taper & bearings are in excellent condition. Bad news is the jaws just look like they got fatigued and started coming apart. Additionally the replacement jaws are proving difficult to find. I read that they could be imperial or metric scroll. Also bad news, you guys will have to now run the 4 jaw for the time being.

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#13

Thank you. Let’s start looking for a new 3 jaw

#14

How would using the 4 jaw instead of 3 affect working on round bar metal?
@hon1nbo are we still down for Wednesday?

#15

It would be a pain in the ass since you need to manually center your workpiece every time: https://littlemachineshop.com/images/gallery/PDF/centering4-jawchuck.pdf

#16

well since the 3 jaw chuck is broken you’ll have to center on your own until we can replace it.
It’s a good skill to develop anyway.

#17

It’s a good skill to have, but since this is a production piece might want to wait if we can or find someone else. I have less experience with that jaw.
If you still want to do that chamfered groove I can still help with that

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#18

The 3 Jaw has now been replaced. @procterc & myself assembled the chuck to the existing back plate. We dialed in the 3 jaw to pretty damn true.
https://m.youtube.com/watch?v=soC_CBJ2BYk

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#19

bravo! thanks guys.

#20

Thank you. Can’t wait to use it.