New PM1236 getting setup

[tino_ale]

Thanks a lot for the time you've taken to explain the subject in depth.

I do indicate the blade orientation (square to centerline) but not height. That could be the issue ? If you have a pointer to the method to indicate please shoot.

I'll also research the rigid compound tool post mount.

I have the Dorian blade holder that you mentioned, blade is only a 19mm high 2mm thick, it will flex very easily. You are right about the blade breaking when the cuts curl and won't slide out of the groove.

I was concerned that maybe I am using too low RPM and too low in feed, if I understand correctly, you can basically not go too slow. I will try power feed in the future too. What kind of advance speed do you usually use ?

Lastly, do you know if I can use a HSS blade or carbide brazed tipped blade in the Aloris BXA 71 holder ?
I would like to train and make sure I get a good hold on parting with cheap blades before I buy the blade and inserts.

Those holders are nice but really for people who have a very low screwup rate and I'm not there yet. The Aloris could be the happy medium.

Thanks again

 

[davidpbest]

That Dorian blade holder is next to useless IMO. It's one of the reasons I discourage people from buying the Dorian starter kit which comes with it. Much better to buy just the Dorian tool post and pick individual tool holders.

You can go too slow in parting and this is typically evident as you dive down to the centerline of the part. I outfitted my 1340 with a VFD, so I actually dial up the speed (the way a CNC would) as I get closer to the center of the part. But my approach is certainly not scientific. What generally happens is that part will try to climb on top of the parting tool if the RPM's are too low - it actually starts to tear the material rather than cut it. I use the term "aggressive enough" with caution here because parting is not a place to start getting aggressive in general, but you do want to keep the tool cutting as consistently as possible, or the material being cut starts to deflect and climb on top of the tool. A lot of this is material specific - brass is a lot different from stainless steel, just to pick two extreme cases.

This video might be helpful to you:

Here's another:

This video covers tool height setting to exact CL of the spindle rotation:

And here's a picture of the tool height setter I made for my 1340:

Mine is a lot fancier than Joe Pie's but if you want to make one, description of how it's made and dialed in is HERE.
Read the descriptions below each photo and you'll get a good idea how to build one and how to establish the height.

As to your question about the Aloris 71, and what to use to practice with, have a look at the following photo:

Notice that the blade clamping top and bottom is wedged shaped to force the blade against the side of the cavity. The side of that cavity is coplaner to to the side of the tool post when mounted. So you can't put a blade in the Aloris 71 that is not flat in profile. Many of the HSS and braised carbide blades are not flat profiles - they are a wedge or T-shape to provide relief at the cutting edge, and in this holder they will align at an angle relative to true vertical. There are flat profile parting blades with braised on carbide that would fit in the Aloris - but you want one that is 1.5 inches tall and 1/8" thick. Finding one that is 1.5" tall could be a challenge (I haven't looked).

That said, the blade shown above (71-125-1BSL from Aloris) takes GTN size 3 inserts. You can find import GTN 3 on eBay for about $2 each in packets of 10, and this combination is probably a good setup to practice and refine your parting skills before jumping to an expensive insert tool like I showed in my earlier post. This Aloris 71 setup with the GTN3 sized blade is exactly what I used to get my head around this topic. The GTN 3 cuts 1/8" wide (3mmm), and that blade, being 1/8" thick, is rigid enough to stand up to lots of abuse.

Hope this helps.

 

[tino_ale]

Man that blade you have on the height setting tool is BEEFY
Mine looks like a chewing gum in comparison (2mm wide).

Thanks for the great info, will watch.

 

[macardoso]

Man that blade you have on the height setting tool is BEEFY
Mine looks like a chewing gum in comparison (2mm wide).

Thanks for the great info, will watch.

Thicker is stronger, but also much higher cutting forces. Note he mentioned a 13x40. My 12x36 could never cut with that.