MT3 Chuck Mount (Baby Bison in the wild)

Not so fast...I just turned that piece of brass and got tremendous chatter. I am thinking that the MT3 shaft is flexing? It looks like this setup will not be good at turning any thing large diameter? I did not expect this. Comments?
 
Might need to tighten that draw bar more than hand tight. Maybe a strap wrench? Then, try the cut again. May need more than a roll pin to secure the handwheel.
 
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I wouldn't recommend hanging a chuck on a MT3 the way you have it, I would expect there would be flex and movement under lateral load when cutting. Not sure why you didn't use a D1-3 back plate to mount the chuck.
 
mksj said:
I wouldn't recommend hanging a chuck on a MT3 the way you have it, I would expect there would be flex and movement under lateral load when cutting. Not sure why you didn't use a D1-3 back plate to mount the chuck.
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You need to be giving me this advice BEFORE you know I am about to make a mistake. This is how a lot of mini-lathes are set up. I was hoping to get really good spindle alignment which I did. Apparently there is a lot of flex in this setup causing chatter. It's a mistake I will learn from. The D1-3 back plate is an option because the chuck has 3 mounting holes (4 would be a problem since the bolt hole circles are almost the same.) This approach was less expensive, or so I thought. I did not foresee this issue or I would not have gone this route.
I could keep this as is and use it for precise small diameter work. Not sure what I'll do yet.
 
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Did not read this post previously, I wasn't quite sure what from the title that it was on the spindle side as opposed to the tailstock. They do make revolving MT3 chucks for the tailstock. You may be able to modify the drawbar for a 5C collet system.
 
I was kidding! You couldn't know what I was thinking of course. That chuck actually came off a revolving tailstock but I need it as a headstock chuck.
Hmmm maybe a 5C chuck build it in the future. I'm intimidated to try a D1-3 taper though.
It is still hard for me to believe there is that much flex in the MT3 shaft? The taper was seated tightly so I can't come up with any other explanation.
 
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rwm said:
You need to be giving me this advice BEFROE you know I am about to make a mistake. This is how a lot of mini-lathes are set up. I was hoping to get really good spindle alignment which I did. Apparently there is a lot of flex in this setup causing chatter. It's a mistake I will learn from. The D1-3 back plate is an option because the chuck has 3 mounting holes (4 would be a problem since the bolt hole circles are almost the same.) This approach was less expensive, or so I thought. I did not foresee this issue or I would not have gone this route.
I could keep this as is and use it for precise small diameter work. Not sure what I'll do yet.
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Try something other than brass.

Brass is the most grabby and least friendly to cut. Also try different tooling or lip your tool bit if using HSS.

Not sure flex is your issue.
 
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I will try that. I also need to check the MT3 taper carefully. To casual inspection is seems tight. I subsequently made the same cut in a larger D1-3 mount chuck without any chatter so that is suspicious.
 
The taper seems fine and grabs tight. Excessive chatter with aluminum, steel and brass of various diameters. I'm going back to a D1-3 mount. I am thinking of using a 6" back plate and leaving it large diameter for a handle. Its hard to rotate a baby Bison. Any thoughts on that?
 
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