Tool Post Holder

Tightening up the lead screw nut solved the problem. The faster speed and .020 cuts worked well. Baron thanks for the suggestion. I got the slot cut. Only have 4 more to go. I'll start on those tomorrow morning.
 
Hi Mick,

Thats good to hear ! But you are going to have to watch that bolt. If its come loose once it will probably come loose again.
Some of the threads on both the bolts and in the holes leave something to be desired in terms of fit. That non setting thread lock could be used with advantage.

However do check the gibs, no point in them being too loose if its going to compromise your ability to cut material properly. Check them at the ends of the table travel, that they don't get too tight there. The most wear is usually in the middle and that is where the table will be at its loosest.
 
Finished the last of the slots this afternoon. The first slot took me almost 3 hours to cut. The last one this afternoon took just under 30 minutes. I think that I am getting better. Time will tell. Have 30 holes to drill and tap and five slits to saw. The atlas/craftsman tool holders that I have are mostly either 3/4 or 13/16 high with some just a littler higher. I decided that a slot to fit the highest ones did not leave enough thickness for the set screws to screw into to hold the tool holders. So I am milling all of my atlas/craftsman tool holders down to 3/4" high. I am leaving the bottom edge as is and only milling the top edge. That's all for today.
 
Hi Mick,

I'm watching and listening ! You know what they say about practice !
 
I basically destroyed two end mills cutting the slots. Before cutting the slots I did my usual online research. There seemed to be two camps. One was don't use an end mill to cut slots/key ways because you will break the tips off of the end mill. Especially if using a four fluke end mill. The other camp's response was nonsense. No problem cutting slots/key ways with end mills. I am with the don't do it camp at this point.

As I was cutting the second slot I noticed a line in the side of the slot. After I finished the slot I took out the end mill and some of the tips were broken off. I attributed this to the problem that I had had with the lead screw nut being loose and the table moving around. Chucked up a new end mill and cut the three remaining slots. I didn't notice any problems during these cuts. Looked at this end mill when I was done and again some of the tips were broken off.

Did some research on sharpening end mills to see if I could save these two end mills. Found that without ridiculously expensive machines sharpening an end mill is not possible. The only advice was to save the damaged end mills for making rough cuts. Then through them away.

The next time I have to cut a slot/key way I will try the drill most the material away then clean up with an end mill method. I'll also look into key way cutters.

On a positive note I finished up one of the holders yesterday afternoon. Took 3 1/2 hours as I stumbled along. The rest will go quicker now that I have the process down. I will post some pictures when I get them all done and cleaned up.
 
mickri said:
I basically destroyed two end mills cutting the slots. Before cutting the slots I did my usual online research. There seemed to be two camps. One was don't use an end mill to cut slots/key ways because you will break the tips off of the end mill. Especially if using a four fluke end mill. The other camp's response was nonsense. No problem cutting slots/key ways with end mills. I am with the don't do it camp at this point.

As I was cutting the second slot I noticed a line in the side of the slot. After I finished the slot I took out the end mill and some of the tips were broken off. I attributed this to the problem that I had had with the lead screw nut being loose and the table moving around. Chucked up a new end mill and cut the three remaining slots. I didn't notice any problems during these cuts. Looked at this end mill when I was done and again some of the tips were broken off.

Did some research on sharpening end mills to see if I could save these two end mills. Found that without ridiculously expensive machines sharpening an end mill is not possible. The only advice was to save the damaged end mills for making rough cuts. Then through them away.

The next time I have to cut a slot/key way I will try the drill most the material away then clean up with an end mill method. I'll also look into key way cutters.

On a positive note I finished up one of the holders yesterday afternoon. Took 3 1/2 hours as I stumbled along. The rest will go quicker now that I have the process down. I will post some pictures when I get them all done and cleaned up.
Click to expand...
You can sharpen the ends, not so easy the helix.
 
Mickri, I have a friend that sharpens his 4 flute end mills, by hand at a normal bench grinder. It is one of the many skills it is possible to learn while progressing in machining. You won't ever get all 4 flutes cutting that way, but you can reuse a wrecked mill a long time that way.

Second, If you are messing up your end mills, carbide or HSS, you are doing something wrong. There are thousands of things to target here. But even on moderately hard steel (Rc 30 and below), HSS end mills will do the trick if you are careful. If you buy centre cutting end mills (which you should), in good quality, you can plunge mill your keyway, and then finish mill it after.

For 40 years I have been in the 'it isn't a problem to mill keyways and slots' camp. It isn't a lie, it just takes skill.

If you are trying to mill a slot in a very hard (Rc45 or higher) or carburized shaft, all bets are off. All that takes is a file to test, and if it skates, then a far more careful approach is required.

Another factor is your setup. With a tiny mill like you have it takes MORE skill to do a great job without wrecking tools. To reduce deflection in your column, take light cuts with a 3/8 end mill - it will result in 1/4 (approx) of deflection force on your column. You will need to run higher RPMs and take plunge cuts. Cutting using the X feed with a 1/2" end mill may be part of your problem.

Here's a good video on plunge milling:

 
The material is 1018 steel. The slot is .400 deep by .750 wide by 2 1/4" long. I had the speed at 400 rpm and each individual cut was .020 or less following BaronJ's suggestion in a previous post. I don't know the feed rate but I wasn't pushing it. Just a steady flow. I first cut one long slot the width of the end mill down to .400 in multiple passes. I then widened the slot with conventional milling, no climb milling, to .750. Each cut was again .020 or less. I will try to take some pictures of the end mills.

I had watched a video but don't think that it was Tom's. I'll watch Tom's video. The video that I watched I didn't think was really applicable to what I was planning to do. The material was 1/4" aluminum and was being cut all the way through. It had you start in the middle by plunging all of the way through then going out to the edge and then going all of the way around. I was cutting a large, deep key way for all intents and purposes.

Cutting the slot had a feel to it like the end mill was alternating between conventional milling and climb milling.

I am open to any and all suggestions. I do not like damaging tools.
 
On a small mill drill like yours (I owned a slightly larger machine than yours for 17 years - it can do capable work) I would have plunge milled to roughing depth, engaging 1/3 of the 1/2" cutter, cutting slowly with lubricant, I'd then advance about 1/4 the diameter and keep plunge milling until I had a nearly 1/2" slot. I'd then plunge mill the rest of it to roughing dimension. You have to be very careful on exiting the slot that you don't catch the cutter - you just cut with a little less pressure..

After that process I'd take the tops of the waves using conventional milling, taking about .010 cuts. Then I'd mill the final depth, not touching the sides. The last operation is to climb mill the last pass(es) taking shallow cuts, .005 with perhaps .333 engagement on each pass until I got the sides to spec.

Plunge milling isn't just for aluminum, or for shallow milling. I once milled cast iron where the guy needed a flat face in between two bosses. the contact area on the HSS mill was just under 2". He had broken 2 mills using full engagement. I plunge milled the surface using .010 steps, and then climb milled the final surface. It took a few minutes to do the job. He had been milling/failing for just under 2 hours.

So plunge milling is fast, uses only the END of the END mill, saving your helix for subsequent sharpenings. It creates far less side pressure on the machine as the only contact area is under the mill, not on the side of the mill. The downside is that you get impatient, and plunge too hard, the *ping*, a cutter will bite the dust!!!

It is possible to make a jig to resharpen the end flutes on a 4 flute end mill on your own bench grinder. There used to be a jig you could buy to do this, similar to a drill sharpening jig. I haven't needed one, because, well, (he said with some embarrassment, ahem) I bought 2 of those expensive sharpening machines you mentioned. What you need is something to hold your cutter to an angle, stop the cutter at an engagement on the grinding wheel, and allow you to advance the cutter for each flute.
 
One thing that I am not is impatient. I don't care if it takes me all day to do something that somebody else could do in minutes.

I had considered drilling out most of the material in the slot and only using the end mill to clean up the bottom of the slot and the sides. I decided not to because I was concerned about the end mill catching on the protruding edges left from the drilling. Especially on the climb side. I could envision a point on the end mill first hitting an edge in conventional milling and then as it rotated hit another edge in climb milling. In hindsight I probably should have either drilled or plunge milled out most of the material in the slot.

I have watched Tom's video on plunge milling. It seems like in most of these videos the machinist is always working with aluminum. I often wonder if what works in aluminum will also work just a well in steel.

This is something that will come up over and over. I plan to make a couple more of the holders. And when I modify the wood cutting band saw I recently purchased to cut metal I will have to cut a key way in a 5/8" shaft for the reduction pulleys. I do have a key way cutting. Have not checked the size.

I will look into the angles to clean up the end mills and give it a try. My thought process is that if something is already broken I can't make it any worse by trying to fix it. A lot of times I am successful in my fix.

Thanks for all your suggestions.
 
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