Craftsman 109 mini lathe, chuck woes

[2stroke1971]

I bought an old craftsman 109 mini lathe a while back. It cost me $50, and I had a lot of fun getting it back into shape. I am well aware of its reputation as a toy heheh. Also, while I would not call myself a machinist, I have a lot of time on "real" lathes at work, so I actually understand the 109's limits and why they are. I have enjoyed fixing it up and making some stuff for it. I had a nice HEAVY little table that came with an old craftsman drill press I bought, and I mounted the 109 to that and put a modern motor on it. (Variable speed DC to come)
The 109 made a very nice truing jig for a motorcycle crank that I rebuilt last year and when I get the variable speed DC set up on it, I am going to use it as a coil winder as well.

So having made as much of a defense as I care to for the practicality of my owning the little old toy, the biggest issue I have is the chuck. It is by far the worst part of this setup. It is the original 3 jaw unit. It has holes for a spanner to tighten it. I made a spanner that fits just fine. I hold one of the chuck blades from the side with a wrench and crank down on the spanner. (I wonder how they "intended" for one to tighten that chuck?) I made some tool holders for it that accept modern cutting bits and while the chuck holds, I can actually make some fair cuts. However, what invariably happens is that just about the time I see a nice run happening, get a half an inch in.... Then run and grab the camera to prove to the world the 109 can cut more than brass, and more than ".0000000001" at a time, the piece comes tumbling out of the chuck. Even a piece of PVC that I was boring the inside out of, not a tough thing for this little lathe to work. SMH. So I guess I'm going to look for an upgraded chuck. I figure I'd make a solid spindle shaft for it if I have to, and thread the end for whatever the chuck takes. I know there are some adapters that people make short of that. Unless I am missing something with the original chuck....maybe there is a proper way to tighten it that makes it grab well?
Has anyone had any experience with the old chucks on these? Do they generally **** worse than the rest of the machine or is mine just bad? I am sure a steady rest would help take the lateral force off the chuck,(such as this little thing can produce before becoming unhappy) but I don't have one and it happens with shorter pieces just as often.

Thanks

 

[1982fxr]

Years ago I asked the old schoolers on a mc site, the guys that were machinists AND engine builders, about using a lathe instead of the proper centers for flywheels.

They collectively lost their ****. Sorry, that's all I got. Glad I wasn't the only one who at least thought it though.

 

[Maui]

The four jaw chuck for that lathe is much more common and does not suffer from the issues you described since each jaw is tightened separately with an allen wrench. I’d simply purchase a four jaw chuck for it. That’s what I have on mine and it works well.

 

[bmwrd0]

The biggest limitation of the 109 is the screwthread on the cross slide. Other than that it is just a small lathe, and people who try to do big lathe things on it are going to be disappointed. That said, the one I had used a Goodell chuck. Not stock, obviously, but seemed to work well.

 

[slowtwitch73]

Could be a lot of things.

I would do a test to see if you are getting full jaw contact on the stock. If not, grind the jaws and lube the chuck.

 

[2stroke1971]

I solved my chuck issue. It was my own....dumbness. I was never sure about tightening the chuck, as to what was the proper way. I Made a nice spanner that grabs the pins on the collar...holding the other part still was a mystery to me. I had been grabbing the flat nut on back of the chuck, or holding one of the jaws with a wrench. Holding the flat nut would loosen the chuck of course, and holding a jaw worked against the chuck jaws moving in. The chuck got really tight, so I took it all apart and cleaned it. I polished the sides of each jaw until they slid really well in their slots while it was apart. In any case, there is a little thumb screw on the pulley that locks it in place, THAT is what is supposed to hold the shaft still while the outer collar is moved. I had seen that screw before, and knew it locked the shaft but I didn't think that was its purpose. (piece changes)
I was able to do a little work to some pieces since and no issues with the piece coming out. Also the chuck is smooth as butter moving in and out.
As for the motorcycle crank, old school method is V blocks and a brass hammer, for my lathe-as-a-crank-truing-rig, the centers I used were right on as I could tell. I got it right around .001 difference between the halves. I haven't run that engine yet, but it feels really nice in the cases. I've built enough 2 stroke singles over the last 35 years to know it is "good enough". For this build, I am determined to do ALL of it. Did the bore myself as well. If it takes a sh*t 5 minutes after I start it, I will chuckle and put it in the corner of the shop until I get back to it.

Anyway, thanks for the replies!