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-   Cutting various materials - bit selection, feeds, speeds (http://www.mechmate.com/forums/forumdisplay.php?f=82)
-   -   Making 700+ holes? (http://www.mechmate.com/forums/showthread.php?t=5260)

digger Sat 06 August 2016 07:13

Making 700+ holes?
 
I will have to make about 700+ holes in baltic birch 1" thick. Hole size is 1/2" and 3/4". How would you do it considering the number of holes? Drilling or spiral cutting? Feeds and speeds?

Thanks
Milosh

lonestaral Sat 06 August 2016 20:25

I would spiral cut with a 6mm dia tool.
I have read that spindle bearings are not designed
for the forces produced while drilling.
Sorry I cannot provide speeds and feeds.

pblackburn Sun 07 August 2016 17:30

Spiral cutting and I would start with a plunge feed and increase from there. Use slight air stream to help keep the holes clear of chips to avoid recutting and heating up your bit. Neither cheap spindles or routers are designed for plunge cutting. Normally you have 2 angular contact bearings and at least radial bearing on spindles designed for straight plunge and drill purposes. The Chinese spindles have a medium set angular contact at the nose and a single small angular at the top. Not sufficient for straight plunging based from calculations for feeds.

I hope this helps

digger Mon 08 August 2016 00:54

It looks that spiral cutting is a logical choice. I had an impression that with drill it is going to be faster. Maybe, but there is no reason to look for a bearing change prematurely.

Thanks for help guys!

Andrew_standen Mon 08 August 2016 06:42

I've done this many times before.
25mm birch plywood.
2.2kw water cooled spindle.
1/4 inch 2 flute compression spiral tool 6mm dia
15000rpm feed down 3000( 118 inches ) cut feed 4000( 157 inches ) , depth of cut 8.5mm per pass.
Profile cut inside ramped . or if your software does it Helical.
Not a pocket cut..
700 holes evenly spaced over a 8 by 4 sheet takes me around 45mins to cut.

You can do it faster, but I don't have to.

At work on our large machines we do the same job in 22mins but we cut at 12000mm per min ( 470 inches ), my machine at home, doesn't like that !

ok , the rpm might be a bit fast but, the tool has lasted well and the cut is good.
at only 2.2kw, something has to give.
we run 9kw spindles at work.

hope that helps.

please let us all know what works for you.

Have fun.
regards
Andrew

digger Thu 11 August 2016 06:09

Thanks Andrew.

I think I will go that way. It is right way to do so many holes with spindle. As soon as I start to cut, I will post some photos.

Milosh

ger21 Fri 12 August 2016 17:38

Quote:
At work on our large machines we do the same job in 22mins

Your making 3 passes, and still cutting a hole every 1.8 seconds?

Andrew_standen Fri 12 August 2016 23:42

We run alphacam advanced router 2016r2 via woodwop5 on a weeke machine.
it's a helical cut.
The cutter does not retract between passes.
More of a spiral plunge. It's 3 rotations at the end of rotation 1 the cutter is minus 12.5mm
at the end of rotation 2 it's minus 25.25
rotation 3 is the final clear out at the same depth.
The cut speed is set to 20mtrs but I doubt it gets over 12mtrs.
The cut is less than a second it s the retract and repositioning that takes time.
It retracts at 11mtrs a min and re positions to the next hole at 60mtrs

most of the time is lost in repositioning ramping up and ramping down.
It's scary fast.
We trim the 25mm sheets in a single pass at 35mtrs min using a 16mm 2 fute compression spiral

I still do things at home on my mechmate that I can't do at work
like running jobs with 0.8mm cutters

cheers Andrew

ger21 Sat 13 August 2016 06:34

I program and run a Morbidelli at work,and use an older version of Alphacam, but our machine is not that fast.
It's also limited by gantry flex in certain cases, and this would be one.

It has a cantilevered gantry, which is a welded square steel tube, roughly 18"X18" (450mm?). On short back and forth moves, like a small circle, the gantry will flex, and oscillate a small amount, which.is very visible in the cut. The closer to the end of the gantry, the worse it becomes.

On the other hand, the machine has no issues cutting cabinet parts at 25m/min.

And similarly, I can do things at home on my $1000 homebuilt machine that I can't do on the $100K Morbidelli.

Andrew_standen Sat 13 August 2016 17:06

I'm still amazed at what I can do at home.
The machines at work have pressure mats. Laser beams. Skirts and brushes around the heads. It's difficult to see what they are doing.
Ok. Granted they are safer than my mechmate but only because
they have these safety devices which cost more than i paid for my mechmate.


I use my mechmate almost every day.(since July 2013)
Not for long runs. Mostly 1 hour a day.
weekends maybe 3 hours a day
It's just a hobby/craft tool.
but it has paid for its self.
I'm more than happy with its capabilities.

It's still in a continuous improvement stage.
Mostly correcting my inaccurate building..lol
now running a uc100 motion controller which works well.
played around with rapid speeds till it got silly then went sensible
and set it at 12mtrs... Most cutting happens between 500 mm and 5m try

Stay safe.
regards Andrew


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