Minor victories, modified AXA-8, first threads on my G0752Z

[WobblyHand]

A while back I bought an Aloris AXA-8 HSS threading holder and blade. Due to a misunderstanding on my part, I found that the holder and blade could not be set to centerline on my lathe. The height from the top of the compound to the centerline was 0.947" and the height from the bottom of the tool holder to the top of the cutter was 0.994". My choices were either to grind the HSS cutter, or mill off the bottom of the tool holder. Decided that milling the bottom was the easier of the two choices.

Milled off the bottom of the holder using a 0.020 radius carbide end mill. Wasn't the smoothest of finishes, but it did cut through the hardened steel holder. I took off around 0.050". I then used a series of diamond honing stones to further polish the bottom surface. It's not quite mirror flat, but it's good enough. Toolholder was sitting on my desk awhile. Today I thought I'd try it out.

Standing in front of my used Grizzly G0752Z, I tried to interpret the threading chart. Thought I'd set up for a very fine pitch, so my first threading on this lathe would be less exciting. After a bit, it started to sink in. Eventually I made a simple, condensed spreadsheet for some common threads that I might make. Since I need to make a screw that is 1/4-40, for a project, thought I'd set up the gears for that pitch. After some awkward moments, including dumping the E clip on the ground, finally got the lathe set up for 40 pitch. For those that might still be following along the settings are: C, I, 36, 40. Have to say, I see why people desire real quick change gear boxes. I'm already considering Clough 42's ELS. Was even more awkward than changing gears in a mini-lathe. I know I'll get used to it, but it's definitely messy and little parts do go flying. It reminds me to buy a couple spare clips and things from Grizzly.

I set the center height of the AXA-8 by using a 1" rod in the chuck and measuring down 1/2 the diameter. I had previously used a micrometer on the rod. Using a dial caliper set it to 1/2 diameter, then adjusted the cutter until it just touched. I have a few thousandths of daylight between the top of the compound and the bottom of the AXA-8. Being lazy, I decided to thread the 1" 12L14 rod at 40 pitch. Did a scratch pass and amazingly enough, it was 40 pitch! Didn't think I would get it the first time.

Threads cut very nicely. Glad I chose a 40 pitch thread for the first threads as it let me get used to the timing for setting the half nuts. An 8 pitch thread would be 5 times faster. Didn't bother measuring the threads with wires as this one was just for fun. I have to calculate what would the pitch diameter be? 1"-40 is not a UNS thread.

So at least for me, a couple of minor victories. Got the AXA-8 set up, and my first single point threads on this lathe. Wish I could clean the 40 TPI threads out. The threads just cut the paper towels and shredded them. Also did a number on the pipe cleaner I tried.

 

[woodchucker]

You can use back gears to slow things up when using faster threads. It gets much easier over time... then you won't thread for a while, and it takes a bit to get back into the rhythm.

That's the beauty of your own lathe, you can concoct whatever thread you want on whatever size piece.

 

[jwmelvin]

I thought about threading on my g0602 once; stared at the gears for a few seconds and moved on to something else. So I know how you felt at first. Nice that you pushed on and did it, successfully too. My current lathe has a gearbox and I’ve threaded a few times. I find it pretty gratifying so far. Maybe I’ll have to have another go at the grizzly’s change gears.

 

[WobblyHand]

You can use back gears to slow things up when using faster threads. It gets much easier over time... then you won't thread for a while, and it takes a bit to get back into the rhythm.

That's the beauty of your own lathe, you can concoct whatever thread you want on whatever size piece.

I was threading at 150 RPM. This lathe can go down to 100, I think, but need to change a belt for that. Kind of a funny beast as it has a VFD. However, there's no back gears on this lathe. But yes, I kept it all slow to learn the timing on this machine, it's different than my mini-lathe. The new threading tool is pretty nice. I'll have to try it at 8 TPI, it's probably more exciting!

 

[WobblyHand]

I thought about threading on my g0602 once; stared at the gears for a few seconds and moved on to something else. So I know how you felt at first. Nice that you pushed on and did it, successfully too. My current lathe has a gearbox and I’ve threaded a few times. I find it pretty gratifying so far. Maybe I’ll have to have another go at the grizzly’s change gears.

It's not as hard as it seemed. Or at least figuring out the settings and gearing. Physically it's a bit awkward and a little messy, but not hard. It's the little clips that bother me, I just don't like the idea of possibly losing little parts in the process. Especially when I have no spares.

 

[woodchucker]

oh, don't worry, you will lose parts. It happens.

 

[benmychree]

Indeed, stuff does happen! I cut a double lead thread with 1" pitch up to shoulder and stuff happened several times, but the result was sucessful/

 

[mikey]

Wish I could clean the 40 TPI threads out.

Did you try a stainless steel brush? The fine ones work pretty good for this issue.

Speaking of those burrs, I own an AXA-8 and it works okay. The blade is canted at a 12 degree angle (but is flat on top) which is supposed to give you adequate relief on the sides, even though the sides of the blade have no relief ground into them. I'm not sure how much actual relief this geometry produces but I do know that on fine threads it does tend to produce burrs. On larger threads it isn't as bad.

I think the advantage to the Aloris #8 is that you can easily adjust for different helix angles. Again, this would mostly apply to larger/coarser threads and doesn't really come into play for finer threads commonly used in a hobby shop.

I tend not to use this tool much at all anymore. The same goes for my Carmex inserted threading tool. Both work fine but for the smaller work that I do, I much prefer a threading tool with 15 degrees of actual relief on each side. It cuts cleaner (nearly burr-free) for me and is very accurate. I suspect that if I was in a production situation, though, I would go with the Carmex tool more often.

 

[Jubil]

As Mikey said, a steel brush works wonders. It helps smooth out the thread also if the finish is a little rough.

Chuck

 

[mmcmdl]

Steel brush , file card , small needle triangular file , triangular stone , scotch brite should all be in your arsenal for cleaning up threads .