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I have been experimenting with my multi-lead thread program on and off for a week.  I’m using some scrap cold rolled steel rod I have sitting around.  They won’t make good taps, but it is convenient.  Anyway, after sorting out some issues with the A-axis stalling, and a pile of gcode issues, I finally had a successful cut today.

The thread is a 4 lead thread with an overall pitch of 40tpi.  This test was done on a middle section of a test piece so it won’t be particularly useful.  The program required 88 passes, and took 5hrs 45mins to run.

I have a few issues to deal with still.  I am getting some deflection in the rod during the threading.  I haven’t rigged up a tailstock for my mill yet, but I think this is going to be required to get good quality threads.  I think I may turn a proper tap blank tomorrow morning, and let the thread program run while I’m away over lunch.  If that works out, I’ll mill some flutes into it, harden it and try tapping some brass with it.  Since it’s low carbon steel it won’t harden well, but it should do fine for testing it on some brass.  I may even try making a matching die out of it.

If those experiments work out, I will drive out to the Metal Supermarket and see if they have any A2 drill rod I can try making a more permanent set of taps and dies out of.  Of course at this point I still have no idea what size of tap I’m going to need for this first pen, so this whole experiment may never turn out to be useful other than as a proof of concept.

I was able to finish up the pen project I was working on.  A couple of bumps along the road, but overall not too bad.  Here is the requisite photo:

As I mentioned in the last post, I needed to rig up a mount for the lathe. It took me a good chunk of my afternoon yesterday, but I finally got something that I’m happy with for now.

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This week I have been working on a last minute project to get a number of pens made.  They are for a friend who is using them at an important document signing at work.  This is probably the last project that my Frankenstein CNC lathe is going to do (as I’ve mentioned in past posts, I am working on mounting it on my mill.)  The pens need to be finished for Wednesday.  So of course one of the stepper motors decided to break today.  I was almost finished turning the barrel of the second last pen, and the drive shaft snapped.  I still have around 10hrs of work to do to get these pens finished so this is more than a little inconvenient.

So I am in the middle of hacking together a mount for my lathe headstock and motor so I can run it on the mill.  The other option is to modify one of the stepper motors from the mill so I can use it on my lathe (they use different connectors.)  I’m not really a fan of doing that since I would just have to switch the connector back again after I’m done.  On top of that, there is obviously a flaw in the alignment of the stepper motor with the lead screw of the lathe since this isn’t the first time the drive shaft has broken.  I’m not really interested in potentially sacrificing one of my mill’s stepper motors to the lathe.

I think I have a solution that will be easy to get working though.  I have some old riser blocks for the Taig lathe which were originally designed to increase the swing over the bed.  I haven’t used them in years.  They do happen to have that nice dovetail on the top specifically for mounting the headstock on.  So I’m trimming it down, and putting some holes into it for mounting on my hold down plate.  We’ll see tomorrow how that works out.  I still need to figure out how I’m going to mount the motor.  I’ll post some photos when I’ve got it figured out, and hopefully I can do all of this and still have enough time to get the pens finished.

It’s been a bit since my last update.  Between the nice weather tempting me to get the bike out and ride, as well as life in general, I haven’t had as much time in the shop the past couple of weeks.  I have a large order of pens to fill this week, so my other projects will be on hold.  I am thinking of documenting the process of making one of my cigar pens for the blog.  This might be a good opportunity since I’m not sure when or if I will be making another of these cigar pens out of acrylic.

Here are some photos of the mill enclosure, as well as the mill in action.

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Today was the first trial of the mill with the flood cooling going.  Apparently I missed a couple of spots with the silicon sealant.  The enclosure sprung a couple of leaks, and I had to do some make shift coolant collection with my collection of popcorn buckets.  I’m waiting for things to dry out a bit before I give it a second round of caulking.

Aside from the leaking, things worked like a charm.  I was making some risers to allow me to clamp my screw-less vise to the table.  They are 6061 aluminum, that I was cutting with a 3/8″ end mill.  I was taking 0.05″ passes at 12.9IPM, and it was leaving a nice smooth finish.  Nothing over heated, chips were cleared away nicely, and the mill didn’t look or sound like it was being worked very hard.

Now that I can clamp the vise down well, I will be working on the lathe mounting plate tomorrow.

I’ve finally finished the enclosure and flood cooling for my mill. I ran into some issues with the pump I initially purchased. It was a 125GPH pump designed for a small pond. Unfortunately it couldn’t handle pumping the coolant up the 4.5′ from the bucket to the flood nozzle. So out I went tonight and picked up a new pump. This one is a 500GPH pump and can handle the height.

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One of the issues I’ve had in the past year with my pen designs is the thread used for the cap of the pens.  Because I have been using a standard thread, the caps require several turns to close properly.  This is awkward, and annoying at the best of times.  One of the solutions is to use a multi-lead thread.  It is a very fine thread (which helps in alignment, and avoiding a loose cap,) that closes quickly.  Unfortunately taps and dies are not commonly available with multi-lead threads.  Because they are one off items, most shops want to charge several hundred dollars for one.

Enter the wonders of CNC mills.  With a little bit of surfing, and digging through the Machinery’s Handbook, I have figured out the basics of how to make a multi-lead thread, and then generate the gcode for it.  After an hour of poking at the keyboard, and much swearing at the computer, I think I have my first threading program.  Hopefully I’ll have a chance to test it on the weekend, or early next week. Once I’ve tested the program out, I’ll do a write up on how I figured out the numbers, as well as the gcode itself.
I should also be able to post some information on making custom taps and dies while I’m at it.

I recently purchased a Taig CNC mill. Along with the standard 3 axis mill, I’ve also purchased a Sherline rotary table to allow me to do 4th-axis work.

Currently I am building an enclosure for the mill. This will help cut down on the noise, as well as keep the coolant and swarf from flying all over the shop. I got most of it built on the weekend, and should have some doors on it tomorrow or Thursday.

Next on the list is to build a mount for my Taig lathe so I can mount it on the mill.  I did convert one of my Taig lathes into a CNC setup, but I’ve never been particularly happy with it.  Hopefully having all the CNC work on one machine will make my work flow a little easier, not to mention more accurate  and consistent turning.

Once I get the enclosure built, I’ll get some photos up.