Milling keyway in Horz. Mill 14" long shaft help

I have to increase keyway length in 14' X 1-1/2" SS shaft. I have a small #2 size K&T mill. Good accurate 40's vintage or newer.
What is the best way to clamp the shaft to the table using the T slot to set the shaft in? I probably made this shaft long ago when I had bigger mills. My concern is the 3/8" wide mill might grab the shaft and pull it even though I'm careful to be sure back lash is removed. Problem with clamping is I'm limited to the other 2 T slots on the table so the strap clamp stud is quite distant from the shaft. Possibly use a milling vice inverted against a fixed stop will stop the cutter from pulling the shaft?
Note; I screwed-up in topic, shaft is 14 feet long!!

Secure end stop is essential,as pushing force is great with stainless......holding down isnt so critical as the cutter forces the work down into the T slot.....at least thats my experience of keying boat propshafts.

Froneck said:

I have to increase keyway length in 14' X 1-1/2" SS shaft. I have a small #2 size K&T mill. Good accurate 40's vintage or newer.
What is the best way to clamp the shaft to the table using the T slot to set the shaft in? I probably made this shaft long ago when I had bigger mills. My concern is the 3/8" wide mill might grab the shaft and pull it even though I'm careful to be sure back lash is removed. Problem with clamping is I'm limited to the other 2 T slots on the table so the strap clamp stud is quite distant from the shaft. Possibly use a milling vice inverted against a fixed stop will stop the cutter from pulling the shaft?

Click to expand...

Several strap clamps with the work nestled into the central tee slot.

Shim the work as required for straightness. Shift the clamps as the work advances.
No need to climb cut. So no worries about the mill grabbing the shaft.

I'm not climb cutting, intend all cuts to be conventional. Using Horz. mill cutter not end mill because existing cut was done that way. Have no problem with straightness. Existing key is 4" long including mill radius, a few more new key cuts were also added. They added key cut on end of shaft, I have no problem with that since I will start cut off the shaft. I'm increasing length of the existing key cut 2" + mill radius on both sides, if it were one side I would start cut in old key slot, being new keys were added requires complete new cut. On short shaft I would cut in one pass but on the start side I'll take light cuts. Not concerned with pushing at end of cut, my concern is mill pulling shaft at start of the cut especially last finishing cut. Will back-up to start with mill out of the shaft, over travel then forward to start location to remove backlash and bring table up to finish depth. That's where I'm worried mill will grab work. Has one time before on larger shaft with larger key. Fortunately it wasn't finish cut and was able to mill out the gouge. But mill was broken and key in arbor sheared. That shaft was only 6' so I unscrewed 2 bolts on end plate, inserted 2 long clamp studs with nut to hold end plate, attached bar at the end of the studs to butt against shaft. But this shaft is 14' long! If I did the same using 10' of all thread I doubt it would do anything since it will just bend under pressure. Clamps studs being so far away from shaft and width of table will result in more pressure on the step blocks than the shaft.

How about long thick bars for the straps, secured using both slots on either side of shaft, with a screw in the center to press down on the shaft.

Mike

Its a very easy job, have a stop block at the end of the shaft so the shaft cant slide if the key is at one end. Use strap clamps( hair pin ) to bridge between the 2 tee slots, you will need 4 one at each end of the table and 2 that you will slide as the cutter works along the 14 inches. Keep the clamps 6 inches away from the cutter and as the distance gets within 2 inches of the cutter shut down and move the bar away.In my shop I don't shut down but OSHA would have a fit if you don't and its dangerous... Restart and go again. You can weld up your own clamps if you don't have hair pin clamps out of 1/2 or 5/8 x 2 bar ...Phil

I did think of very thick bars to bridge over the shaft with no screw, just a hole for stud on each end. T slots are big enough to accept 5/8 T bolt or T nut. I would think screw in center will weaken bar and screw not provide as much force as the bar itself. Not sure what a hair pin clamp is but I assume it is something like a split bushing with ears welded to both sides of the split. Might work if placed at the end of the table in the opening for inserting T nuts. I screwed-up in the title, shaft is 14 feet long. I just added note correcting shaft length.

Froneck said:

... Not sure what a hair pin clamp is but I assume it is something like a split bushing with ears welded to both sides of the split...

Click to expand...

Think about a thick piece of steel bar folded in a U shape.

Paolo

Take a piece of 1/2 x 2 flat bar 26 inch long heat the middle and bend ( the easy way) so the lags are 5/8 apart like a u and you will have a hairpin bar or clamp about 12 inches long...use 2 tee nuts and studs, one at each end and clamp your shaft with the bar over it...easy...Phil

I think this is similar to what you're asking. My mentor and I did something similar. Hope this helps. It worked great.
https://youtu.be/apWIIXCx64w

I looked at the video, problem is my error in listing the shaft in the topic as 14 inches , it should have been 14 feet, It was 1-1/2" round and keyed 3/8" but customer wanted 3 Key slots extended on both sides. I used 4 forged goose neck clamps with 5/8" forged T bolts tightened as much as I could possibly pull an 18" long wrench. Plus I have quite a few of these forged clamps that are somewhat arched, slotted center with notches with a block that aligns with the notches for the stud and also used forged T bolt, used 2 of them. I cut 1/2 the key, reversed spindle and cutter and cut other half so both sides were cut in conventional direction. To complete the cut I backed to the start engaged the feed, spindle and all feeds start with electric push button that controls single motor. With feed on slowest possible I turned on and off the motor when it was very near the start in climb direction. When I seen small gap I placed a strip of heavy paper (.005") in the slot and start/stopped spindle as the feed brought it close to the start of the Key as the spindle and feed coasted to a stop. The stop button on my mill is also E stop in that if pushed in all the way will energize a reversing contactor that is connected to a sail switch so that the moment the motor shaft becomes 0 RPM the power is removed and spindle stops. I continued the on/off switching until cutter grabbed the paper while keeping my hand on the stop switch to e-stop if it became necessary, remover back lash, lowered cutter .003" and finished full cut. Shaft was completed and waiting for customer pick-p. Thanks guys for your suggestions!!
Frank