Horizontal Grooves With A 10f

cdhknives

cdhknives

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I was looking to cut some long straight grooves in a tube (AR tubular handguard to be exact, anodized aluminum). I've seen several people lock the headstock and run the carriage back and forth with a bit rotated 90 degrees in the tool holder to put shallow grip grooved in handles and the like. This cuts shallow grooves horizontally down the length of a small part. with the length and number of grooves I am looking at, hand cranking is less attractive.

My tool would be a V ground large radius (1/8" to 1/4" radius???) nose square bit to give me a shallow rounded bottom groove.

My question is if I can pull (unlatch) the bull gear pin, leave back gears disengaged, and use the feedscrew to run the carriage back and forth. I would lock the bull gear with the lock pin, and use the index holes for indexing as designed.

Are there any pitfalls I need to watch for, like chatter and workpiece flex? I think I have holding the tube worked out, but it will be near 12" long and only supported on the ends unless I break out the follower rest.
 
Tool bit should be ground like a metal shaper (planer) tool. If you are cutting deep, be sure to include enough side clearance.

I would disengage the change-gears and rig up a variable speed drill motor to your leadscrew. With the spindle locked (and the lathe powered off), engage the half-nuts and drive the carriage with the drill on the leadscrew.

Yes, you may need to rig up a follower rest to reduce flex.
 
I'm curious as to why you are not recommending using the leadscrew drive train? A cordless drill will have squat for torque in comparison, and starting/stopping can be managed fairly precisely. Is there a strength issue in the geartrain and QCGB?
 
I've done this on my lathe and found that the less geartrain movement, the less vibration into the workpiece. Oh, and I used a corded variable speed power drill. You can always open the half nuts and finish the cut to a precise location with the carriage handwheel.
 
If I understand correctly, you want to lock the spindle but use the geartrain to drive the leadscrew. On my Atlas 6", the bull gear pin locks the spindle to the drive pulley. Disengaging the drive pin also disengages the drive train which will prevent the leadscrew from turning. Looking at a parts diagram for the 10f, it looks like it operates the same way.
 
Is it possible to run the lead screw with the spindle not turning? If so, I didn't know that. Been 40 years since I owned an Atlas.
 
how big and wall thickness is this tube? 12" is not much, crank it by hand and do shallow cuts. I think monkeying around with trying to feed is going to take longer.

You could quickly make up some bracing at the half way mark to maintain straightness, you really don't need a follow rest I think. The piece below is solid bronze and only 4: long so I didn't have to worry about flex. Maybe you could find solid stock to fit inside the tube to reduce flex?

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I'm thinking I can support the tube independant of the spindle but maybe not stiff enough...I need to assemble and see. You're right, the spindle has to turn to drive the leadscrew gear train...I had it in my head the notches on the left of the 4 step pulley locked to the far left pulley but there's a bearing in the way when I look at it. So much for visualization and daydreaming when I'm at work...
 
I have done the power feed thing many times and many different ways. Here is another option:live spindle.jpg I made a ball bearing "live spindle" that the chuck threads onto, and has a Morse Taper at the other end which is seated in the lathe's headstock spindle bore. This allows you to keep the lathe running (and complete geartrain) while the chuck just sits stationary.


Matt
 
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