[Mag_vest]

Hi!

Just starting a project of my own!
I'm building it of 160x80 extruded profiles, and 16mm steel. And some 10mm in the z-axis.
I will use Hiwin HGR20 on all sides. 2x on each side of the y axis. The y axis will have 2005 ballscrews and z and x will have 1605 screws.

As we have a small plasma table at work, cutting the steel is no probelm. (SwiftCut machine, and Hyperterm, powermax125)

Then I started wondering about motors.
And found out that i need 3N and 800rpm that will give me 4000mm/min.
The gantry will be aprox. 60kg.

Does this sound like just crazy or somewhere near a ballpark?

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[Mag_vest]

Threading the profiles, the manual way. They are to expensive to risk a broken tap.

Attachment 327678


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[ger21]

5mm pitch screws are not the best choice.
10mm pitch screws are much better for a router.

[Mag_vest]

Okei. I guess that I can get some problems getting the speed i need.


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[ger21]

Yes, 4m/min is not very fast for a router.
10mm pitch will give much better speed.

[Mag_vest]

Culd it be an option to gear up the motors. Say 1:2 one rev on motor is two on the screw?


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[ger21]

Yes, that will be equivalent to the 10mm pitch screws.

[Mag_vest]

That was what i was thinking.


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[stargeezer]

Hi Gerry. Do you really run your router at 4 meters a minute? I'm using 5 start 1/2" acme screws on my plate maker which I think is around .5" per revolution, so I think that's in the same ballpark + around 3mm a rev., which is ok for rapids in my mind, but I can't imagine doing any cutting at that speed.

Mag-vest - what sorts of material will you be cutting?

Thanks guy's, I'm just trying understand these feeds things better.

Larry

[Mag_vest]

Hi!

The plan is to cut wood and aluminium mainly, maybye some foam and carbon fibre.
And test steel to se the result, but that is just an experiment i want to test.

I think i want to use pully and belts for the motors. Then i can easly change the gear ratio from 1:1 -1:2. I will make the motormounts adjustable for belt tension with different diameter of the pullys.

Managed to cut the two plates for the bed today.
And I may get the rest of the aluminum today!

Magnus





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[stargeezer]

All that except the steel sounds great and very do-able. I think your weak link will be the belts. Particularly when you try steel - you just may strip the teeth right off the belt. I'll tell you that this won't happen with small 1/8
" end-mills - they just snap off. Cheap can equate to insurance with end-mills.

I'd also suggest that when you start cutting to take much more shallow cuts than you think are required and increase the chip load as you gain experience. Experience can be measured in broken end-mills. For that reason I always suggest starting with the cheap Chinese 1/8" end-mills and move onto more expensive end-mills after you gain that all important experience. It's also important to stick with one media until you honestly feel that you've mastered it - in my opinion.

You mentioned carbon fiber - please make dead certain that you know and follow every safety precaution while handling that stuff. Any fibers air born are very dangerous. I had a 37 year old friend who passed away last year from inhaling the stuff while building RC model airplanes in his basement. His wife and kids are being very carefully watched for any of the well known side affects, but so far are healthy. It's truly wonderful stuff, make certain you know the risks. For my part, I won't cut it with a mill or use a power sander on it and always wear a proper respirator - not one of those paper dust masks. OK, that's enough of that for now, I don't mean to scare anybody, just know the risks, they are very real.

[Mag_vest]

Thanks for advice! The steel cutting will be an experiment when I get it upp running, just to see the result.

I think that is is a god routine to use proper protection gear when working with any processes that make dust. And altso know the properties of the material.

I work as a service guy for cnc cutting tables in Norway, plasma and gas tables. Sizes from small 1250x1250mm tables up to 10m wide an 60m long tables. With this comes a lot of knowledge about stuff you are talking about.

Plasma dust and fumes is nasty stuff to work with. I hate dry cutting tables.

I think the clue is knowledge, proper gear, and if in boubt, get datasheets on stuff. They say alot sbout how to treat stuff. And altso risks about it.

But again, thanks for advice.






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[Mag_vest]

The bottom frame plates test mounted, now i can see the footprint of it!!

Attachment 327866


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[moparx12]

Your build looks very similar to what I am trying to do. I think i might go the 1610 ball screw route though and direct drive like Ger mentioned. I'll be watching this thread closely!

Why is it that some use ACME threads on the Z? Do routers need the added plunge force capability they provide? Do you think will the OP have a problem with the 1605 he plans to use on the Z axis?

[ger21]

Hi Gerry. Do you really run your router at 4 meters a minute?...............................I can't imagine doing any cutting at that speed.

4m/min is only 160ipm. I've done 3D finishing passes at 175ipm, which is as fast as my machine will go. I would cut much faster if my machine was capable.

At work, on our industrial router, we typically cut at 15-20m/min.

[Mag_vest]

I come from a gas/plasma world, we cut fom 100mm/min up to 5000mm/min++, and have rapid speeds of 34m/min.
Its amazing to se 10tons of cnc machine at that speed..

But here we are at the core of why i started this thread, to get inputs and learn something on the way.

I got my linear bearings today , 4x 1200mm, 2x 900mm and 12 blocks.

I am altso thinking of maybye go for servos/encoders instead of steppers.

But nothing about the electronics is decided yet.

Only thing i have is a pc dedicated for controller and the spindle with vfd. Both for free.

Can you see the pic's? Attachment 328014


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[moparx12]

I can see the pics. Where did you get the free spindle and VFD? I like that price! The one with 2 bearings on it, is that a 20 or 25mm? Another thing, how did you decide to do the machining on the ball screw ends? I see you have steel plate but will you use the fixed/supported blocks the Chinese suppliers provide?

[Mag_vest]

The spindle and vfd i got from a customer who was going to throw it away, its an old Presice SC60 spindle

All the rails are 20mm.

The ballscrews have 1200mm threads and 67 mm of machined ends, in total 1267mm. I got them from a Swedish supplyer.

For supporting the screws i will make holes in the steel plates for flange type bearings.
The positions was marked out with a pneumatc needelmarker together with the boltpattern for the alu extrutions. This was done by the cuttingmachine when i cut the steel.
I did not cut those holes for two reasons.
A hole cut with plasma is not straight, and i want to have the option to controll measure when i get the gantry in place.


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[moparx12]

Good deal! Question for you on the flange bearings: Are you using one end fixed/ the other end floating like all the Chinese companies offer? Im confused on figuring out what width to make the plates (length of extrusion) so that the bearings match up with the threaded length of the ball screws.

[Mag_vest]

Hi again, long time without any updates.
One side of the bearings will be floating. This makes it easier to get the correct length.

I have got the rest of the aluminum now and started to test fit the complete frame.

And i have decided to go for Mesa electronics, so i orderd a 5i20 board and a 7I37TA to start with.

I can get 4 dc servos for free. Bautz motors. 4000rpm and 5.3 amps. I think this could be over overkill. But they are free, if i use them.

Any thougts?

Magnus
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