[MichaelGolden]

Henry, thank you very much for the help. I wasn't sure where to start. I'll try and nail down the aluminum before trying any inconel. It will take me some time before I'm ready. I'm looking into the design of a small turbofan right now.

[Zenji]

Back in my cadcam days 12 years ago, the GARR brand were always good on price to cutter life ratio.
The only drawback was relieving the shoulder of the cutter with diamond wheel to reach to deep corners.
Inconnel will be like stainless i would think, 3 or 4 sequential cutter length to reach the depth with decreasing depths as tool overhang grows, fresh coolant mixed slightly rich? maybe?
Remember, once a carbide cutter starts to 'buzz' the corners instantly shatter minutely, it can get expensive to cut tough metal.

[hjl4]

Funny you mention GARR. In the first video I posted where the slow milling is taking place, it just so happens it's a GARR 1/16" 2 flute. I agree, they make some of the best cutters. A little expensive but worth every penny. I had tried a Kennemetal one and it broke within a minute. To this day the GARR is still going strong.

[Zenji]

This may be a clearer set of instructions; 35 metres per minute max, solid carbide, 0.025mm per tooth feedrate, half cutter radius max depth.
These would be max figures, if you push solid carbide it wont flex like HSS, it just snaps in a blink.
Attachment 242394
You could build a simple tool and cutter grinder in a similar fashion to a valve grinder, a diamond wheel on an old induction motor and a freely rotating collet chuck to grind the relief above the flutes.
As each cutter stage gets longer the speed, feed and depth of cut should decrease proportionally, sort of, to slow and carbide may snap in which case depth is reduced.
On your cadcam you could cut each stage as a 3 axis pocket cycle sub program and use an incremental 4th axis index repeated with a count in the main program.
The final cuts leave .08 on the walls, use a .03 Z axis stepdown, let it run all day and you will be rewarded with a mirror finish.

I cant wait to see it done!
Maybe make a few small, simple parts with scrap stainless to get the hang of difficult metals > COOLANT! very, very important it's mixed right or a shade rich.

Dirk

[MichaelGolden]

I re-drew and setup a new cad file over the weekend. (That 4 inch handmade aluminum compressor earlier in this post.) I'm going to re-make it and the rest of the entire compressor if possible.

I figured out how to pattern in between the blades. I can do two "simple" passes with a .05 stopover using a 3/16" bit, while leaving at least 0.03" thickness on each side of the blades. But it leaves quite a bit behind the tip of each blade. So maybe a second or extended roughing operation would be necessary. The blades are 1" long and they are the longest blades for this design. (Front of the engine) So I will require a cutter with a length of 1.25"

Unfortunately the blades are so twisted im still restricted to 5 axis milling for even the roughing paths. :/

I really like that cutter grinder idea. I can buy the generic hss coated mill bits in town. So If I can get enough length out of them that would definitely be an option for me.

I would really like some nice GARR bits. But probably not the best thing to learn on.

My coolant is on the to-do list. I have a simple water pump and hosing I just need to find a container to bolt under the table and hook it up!
I have a couple other things to do. The trunnion table isnt completely finished. I'd like to make another helical coupling from steel to replace the junky aluminum one tilting the bed. And have some shimming and tramming left to do. I was surprised it was as capable as it was on the first cut.

But I jumped the gun again and already bought some 4" and 5" solid aluminum round the other day. So its just a matter of small jobs and free time before I go in for another try.

[Zenji]

Cool, good move leaving .03 inch (.8mm)
It's been so long now, but i completely neglected to mention semi finishing, critical to a job like this, i am truly sorry.
May i recommend you rough with an endmill and finish with a ballnose?
Attachment 242634
Again, sorry for the bum steer on finishing, you seem like a switched on machinist i'm glad you erred on the side of caution.

Edit, the drawing is wrong, reduced diameter on the tip lowers the surface speed, not rpm.

[hjl4]

Hey Michael, just thought being that your from Alberta, you can find Garr Tools at Essentra. End Mills, Face Mills & Accessories | Brand: Garr Tool
Not the cheapest.
Also try Acklands as they have some too. Always check Ebay as sometimes you can find some pretty good deals.
As I said before my favorite for quality end mills at cheap prices is CTP. Example............ CTP - Industrial Surplus Tool & Supply Easy ordering and you get your stuff within 3 days.
By sharing this link here, I'm afraid I am giving away one of the cheapest places to get high quality tools cheap, as he has limited quantities as you can see.
The Fullerton cutting tools are also excellent stuff. Browse through and just get what you think you can make use of.
Good day Michael.

[MichaelGolden]

Cool, good move leaving .03 inch (.8mm)
It's been so long now, but i completely neglected to mention semi finishing, critical to a job like this, i am truly sorry.
May i recommend you rough with an endmill and finish with a ballnose?
Attachment 242634
Again, sorry for the bum steer on finishing, you seem like a switched on machinist i'm glad you erred on the side of caution.

Monkey see, monkey do. Haha.
I've learned a lot of what I know by looking into the advanced tool path videos of blisks and impellers posted on YouTube.

I'm planning on finishing with a ballnose. I'm not sure what size yet. I'll have to play around with it for a bit. I don't want to just do two quick passes at the base just because I like the look of small flowing passes.

[MichaelGolden]

Hey Michael, just thought being that your from Alberta, you can find Garr Tools at Essentra. End Mills, Face Mills & Accessories | Brand: Garr Tool
Not the cheapest.
Also try Acklands as they have some too. Always check Ebay as sometimes you can find some pretty good deals.
As I said before my favorite for quality end mills at cheap prices is CTP. Example............ CTP - Industrial Surplus Tool & Supply Easy ordering and you get your stuff within 3 days.
By sharing this link here, I'm afraid I am giving away one of the cheapest places to get high quality tools cheap, as he has limited quantities as you can see.
The Fullerton cutting tools are also excellent stuff. Browse through and just get what you think you can make use of.
Good day Michael.

Thank you sir! I'll have to buy some tonight after work.

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[dmauch]

I saw somewhere that you are using the cnctoolkit to generate the G ciode for your trunnion table . Can you send me the plugin so I can try it?. I have a 5 axis controller using the G540 and the G251. I have a cheap Chinese 4/5th trunnion table that works well. My friend has a copy of powermill so he made the G code file for me. I would love to use gmax and the cnctoolkit but so far no one will make a plugin that will work with a trunnion type 4/5th axis.
Here is a video on my milldrill setup: 5 axis Machining of a dome on a mill drill - YouTube

[Zenji]

Hi again Micheal, just thought I'd share this nice trunnion table i spotted at youtube:
https://www.youtube.com/watch?v=zRhSQjuyumM
The simplicity is beautiful, if only there was a method to remove the backlash from the gear teeth.

[neilw20]

Backlash? Put a spring loaded interposing gear between pinion and table, or spring load stepper assembler directly against table.
As long as the spring loading is stronger than the cutting force backlash is gone.
Or, like the big end of town, put a resolver on the table, a drag brake, and use dual loop servo system. Now that would be a new learning curve!!
Same for the tilt axis.

[jchristopher]

What an awesome thread, thanks!

[MichaelGolden]

Hey there, sorry for the late reply. Actually I havent done anything special with the gmax script. I learnt the trick is setting your work exactly as the code was generated for.. (Actually the other way around) So if your A and B axis are aligned exactly like I have this one setup. The offsets would have to be set to 0. But of course your chuck/fixture pushes the work out. You will have to carefully measure your actual part to the 0,0,0,0,0 point. So your 3d file has to be setup at the exact same distance to zero from the y axis.... Or whatever orientation you have yours setup. You might have to reverse some of your axis too. I had to step through the code one by one to figure out which ones I had reversed.

And remember. Your gcode image in mach3 should look like gibberish! It doesnt compensate for the A and B axis in mach3.

But honestly im not an expert with the script. I just mentioned it because it would be neat if more people used it like you say.

[MichaelGolden]

Hi again Micheal, just thought I'd share this nice trunnion table i spotted at youtube:
....
The simplicity is beautiful, if only there was a method to remove the backlash from the gear teeth.

Yeah there are quite a few on there! I'm actually having vibration issues with mine cutting steel now. The aluminum coupler isnt rigid enough. It worked great with plastic. But cant take the cutting force as well in stronger stuff. Been taking light cuts.. So I have a beefier harmonic drive on the way and I just started upgrading everything to 3/4" steel plate. I've been using it as a 3+2 axis machine. Its been pretty fun setting the parts up for multiple operations in one go!

Here's some photos of the new setup I have planned.

[MichaelGolden]

Backlash? Put a spring loaded interposing gear between pinion and table, or spring load stepper assembler directly against table.
As long as the spring loading is stronger than the cutting force backlash is gone.
Or, like the big end of town, put a resolver on the table, a drag brake, and use dual loop servo system. Now that would be a new learning curve!!
Same for the tilt axis.

I forgot to mention im going to be trying out servo's with the upgrade.
I've been thinking about trying the spring idea with the worm gear. Maybe with an additional tension adjustment by a bolt. It has pretty good accuracy when pressed in tight. But you can hear the high/tight spots in the gearing. Eventually I'll be replacing the rotary table with another harmonic drive though.

And I think you're right on the money with the high drag. Would also be great to come up with some sort of air or hydrolic ram to lock positions between rotations.

[neilw20]

Lock systems:
I have had some experience there.
Be very aware of the cutting forces and measure some forces and holding power of the locks.
Using variable air pressure, on a disc brake, like a pushbike brake, for instance, begins to show how much locking force is needed for a given cutter.
Nothing fancy. Just lock a job to the table and find the limits. Then increase air pressure and find new limit.
Small 4WD car compressors readily make 150-180PSI.

You will very quickly learn how much holding force is required, even for a 1/4" (6mm) cutter.

I use an air operated drawbar on my 4th axis table. Unlock, move to new position (always in the same direction) then lock it.
Air solenoid operated from and auxiliary output, like the coolant plug is a quick fix. Just use M8 to lock, and M9 to unlock.

[MichaelGolden]

I may be able to avoid locking systems for now. I've seen the exact same technology (harmonic drive 4th axis) being advertised specifically without the need for a locking system. I'll know for sure very soon. Waiting on the servo pack connectors right now. Everything else is pretty much ready to go.

[MichaelGolden]

Is that a maple leaf engraved on the plates there?

why yes it is just for fun