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armedandsafe
01-06-2012, 12:42 AM
I would like to cut a slit in the side of a 7/8-14 rod, 0.675" deep, 0.030" minimum, 0.060" maximum with a flat bottom.

I have an HF 6x10 lathe, an HF 3-in-1 mill/lathe, a broken bandsaw, an HF 6" chop saw with a 0.045 blade, a drill press and a need for 100 of these. I'm not a machinist by any means, so keep it fairly well to a real beginner's level, please. :D

I'd rather not buy a chop band saw, unless I really have to.

Thank you.

Pops

LKeithR
01-06-2012, 12:48 AM
Using an end mill is one way but given the width to length ratio of the slot you'd have a lot of trouble with breakage. A slitting saw of the correct thickness is probably your best bet. Depending on how rigid your machine is take 2-3 passes to finish depth...

armedandsafe
01-06-2012, 12:51 AM
Using an end mill is one way but given the width to length ratio of the slot you'd have a lot of trouble with breakage. A slitting saw of the correct thickness is probably your best bet. Depending on how rigid your machine is take 2-3 passes to finish depth...

Talk to me about that slitting saw. In the lathe, in the mill, a separate saw??? I've seen the blades in the research I've done so far, but not much on the use of them.

I tried the end mill thing and ran out of tools. ;)

Pops

RussZHC
01-06-2012, 01:01 AM
http://www.gadgetbuilder.com/

that's the home page, seventh paragraph down, there is mention of what I think you want to do...scrolling over words in a couple of sentences gets you photos of set-up

armedandsafe
01-06-2012, 01:15 AM
http://www.gadgetbuilder.com/

that's the home page, seventh paragraph down, there is mention of what I think you want to do...scrolling over words in a couple of sentences gets you photos of set-up

Now we're getting somewhere. Keep 'em coming. I'm getting the idea.

A holder for the 2.5" rod might be interesting, but I have a couple of ideas, already.

Pops

rdfeil
01-06-2012, 01:49 AM
Pops,

+1 on Keith's suggestion. Get a slitting saw and an appropriate arbor for your mill. Hold the part horizontal at the proper height and feed as needed.

Arcane
01-06-2012, 03:29 AM
You haven't given enough information on the dimensions and shape of the slot.

KiddZimaHater
01-06-2012, 09:05 AM
Use a slitting saw. Make sure the teeth are turning in the right direction. Low rpm. Make several passes.
http://mikesworkshop.weebly.com/uploads/4/3/5/0/4350192/3523242.jpg?549

baldysm
01-06-2012, 01:26 PM
Some one suggested an end mill, but said that you would have problems with the end mill breaking. With a smaller than 1/16" diameter endmill thats over 5/8" deep, thats an understatement. You can't buy a end mill off the shelf that will cut it. It'll take you hours to cut even 1 slot since you would be unable to take any real depth of cut.

This job is what a slitting saw is designed for. You do need to go slow, the diameter your cutting with is considerably larger than most end mills. I would probably take full depth all at once. It's not very deep for a slitting saw. You do need to feed slowly though.

You will find that you are not cutting with all the teeth. You'll find that some teeth will be cutting, and many won't take anything. Just the nature of the beast with tolerances and things not being perfectly concentric.

The only problem you might have is the ends of the slot. The ends of the bottom won't be a square corner, best you can do is a radius the diameter of the saw your using. If the slot is end to end on the part, it's not a problem.

armedandsafe
01-06-2012, 01:53 PM
You haven't given enough information on the dimensions and shape of the slot.

A slot/slit into the side of a round, threaded rod. The slot is 0.675" deep, 0.030" minimum wide, 0.060" maximum wide, with a flat bottom. The sides of the slot/slit are straight and parallel to the face of the end of the rod. The bottom of the slot/slit is flat, rather than curved, as opposed to what a straight plunge of a circular blade would leave.

If I had one, I'd photograph it, but I haven't succeeded cutting one, yet.

Pops

armedandsafe
01-06-2012, 02:04 PM
{snip}
The only problem you might have is the ends of the slot. The ends of the bottom won't be a square corner, best you can do is a radius the diameter of the saw your using. If the slot is end to end on the part, it's not a problem.

What I was thinking is passing the work piece under (or, over) the saw blade, and passing all the way through, to give me the flat bottom. Of course, what I think will work doesn't always work. :D

Pops

Bob Fisher
01-06-2012, 02:29 PM
I feel for you, needing to do 100 with the tools you have, but if you have the time , I guess it can be done. The best option, as has been mentioned, is a slitting saw. Better buy a good one or several others if you want to finish. AND use a coolant. Bob.

danlb
01-06-2012, 02:38 PM
If the slot is going the full length of the rod then the idea of running a slitting saw the length of the rod is perfect.

If the slit is going only 3/4 of the length, then you would be able to come close by running the saw down the length till the center of the saw passes the 3/4 mark.

If the end of the slot needs to be 90 degrees and square, you will need to use some sort of scraper or broach to get rid of the final curve.

Dan

GadgetBuilder
01-06-2012, 02:46 PM
Seems like it will be difficult to hold. The work is 7/8" threaded 14tpi. A slot 0.675 deep leaves little material to hold things together. Considering the thread depth you'll only have about 1/8" left. Not enough to hold by the ends and any pressure across the slit wouldn't work out.

Perhaps a fixture, rectangular material threaded to hold the 2.5" length near one edge, with something like split cotters on the side opposite the slot. Hold the fixture in the mill vise, with the slot out to the side enough so the saw just clears the vise. This might allow you to slit the complete length.

Thin slitting saws tend to drift sideways and break if you try to cut deeply in one pass. Best to use a saw toward the thicker end of your range and make a couple passes to get to depth. At low RPM the saw will last a long time, run the speed up and it will dull quickly.

I'd expect this to take a long time -- slitting is slow work, at least in my shop. Not something I'd volunteer to make 100 of ;-)

danlb
01-06-2012, 03:43 PM
I did not bother to draw it to scale, but it occurs to me that a .060 wide slot that goes .675 deep into a threaded .8750 rod may run into problems.

The minor diameter of 7/8 - 14 will be around .798 The slot will come close to cutting through at the corners.

It would be worthwhile to do a scale drawing or CAD.

Dan

armedandsafe
01-06-2012, 03:47 PM
If the slot is going the full length of the rod then the idea of running a slitting saw the length of the rod is perfect.

If the slit is going only 3/4 of the length, then you would be able to come close by running the saw down the length till the center of the saw passes the 3/4 mark.

If the end of the slot needs to be 90 degrees and square, you will need to use some sort of scraper or broach to get rid of the final curve.

Dan

Cutting parallel to the end face of the rod, not the length. A slot/slit across the width of the rod, not the length. Looking at the side of the rod will let you look down into the slot. Looking down the length, you will see only an edge of the slot.

Pops

Toolguy
01-06-2012, 04:03 PM
That's easy then. Use a vise jaw on the fixed side that has a V groove to keep the parts all the same height and horizontal. Stick the rod out the side of the vise 3/4 or so with an end stop and run the slitting saw through in one pass - full depth.

armedandsafe
01-06-2012, 04:59 PM
That's easy then. Use a vise jaw on the fixed side that has a V groove to keep the parts all the same height and horizontal. Stick the rod out the side of the vise 3/4 or so with an end stop and run the slitting saw through in one pass - full depth.

That is what I am now envisioning. All I have to do is get a vise on my lathe. hmmmmm More tool building? Aw, shucks. :D

Let's see if this will help some of the others envision the slit I want:

http://i55.tinypic.com/264otp1.jpg

Pops

Paul Alciatore
01-06-2012, 05:47 PM
OK, you are going to cut a slot 0.675" deep ACROSS a 7/8-14 threaded rod. Facts:
7/8" = 0.875".
0.875" - 0.675" = 0.200" left after this cut.
But the depth of a 14 TPI thread is about 0.046" so you will have only about 0.154" left of solid material below the thread's minor diameter. That's only slightly more than 1/8". So you will have little of the strength of the original rod left.

How would I do it? Definitely a slitting saw. On the mill. Saw horizontal in the vertical spindle and hold the work vertical in a vise. Probably two passes but you may get away with one. If doing a bunch I would arrange a stop in or below the vise jaws so I can load each one quickly to the same vertical position. Use aluminum scraps to protect threads in vise jaws. Or three nuts, two locked together at top of vise jaws and one loose below near the bottom of the vise jaws.

armedandsafe
01-06-2012, 07:26 PM
OK, you are going to cut a slot 0.675" deep ACROSS a 7/8-14 threaded rod. Facts:
7/8" = 0.875".
0.875" - 0.675" = 0.200" left after this cut.
But the depth of a 14 TPI thread is about 0.046" so you will have only about 0.154" left of solid material below the thread's minor diameter. That's only slightly more than 1/8". So you will have little of the strength of the original rod left.

How would I do it? Definitely a slitting saw. On the mill. Saw horizontal in the vertical spindle and hold the work vertical in a vise. Probably two passes but you may get away with one. If doing a bunch I would arrange a stop in or below the vise jaws so I can load each one quickly to the same vertical position. Use aluminum scraps to protect threads in vise jaws. Or three nuts, two locked together at top of vise jaws and one loose below near the bottom of the vise jaws.

The small portion "below" the cut will never have any pressure on it. It has to carry only its own weight. It acts only as a gude for the cutter to slide up into.

My mill is a little HF 3-in-1, the little "Yellow Boy." Round column, so it is really hard to get it to lock against side forces. Not much power, so I have to really baby it. Top speed 2500 rated, probably a bit slower than that. I might try that anyway and feed the rod into the blade from the front, rather than the side.

It is going to be interesting, I can tell. I have a production batch going together now, so I won't get to experiment with the new design for awhile. I'll post back when I do get into this experiment.

In the meantime, keep 'em coming, please. I'm learning metal isn't as forgiving as electrons. :D

Pops