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View Full Version : Skimming yer bed.... does anyone use a fly cutter?



HankMcSpank
08-09-2013, 01:37 PM
Just wondering how the majority level the bed/table of their CNC machine? ....does anyone use a fly cutter? If so, what spindle are you using with it (because I'm figuring that the chinese spindle's RPM don't go low enough & fly cutter would likely stress the bearings.....not to mention being dangerous!)

Looking at you tube videos, the end finish seems far superior when using a fly cutter (vs say a 6mm endmill to level the bed)

Jonathan
08-09-2013, 01:54 PM
If I recall correctly Jazz uses a flycutter in the normal 2.2kW spindle as his bed is made up of strips, so the fly cutter can be set to the diameter which cuts the whole strip in one pass.

I'd be worried about the lack of balance when using a flycutter, so I just use a 10mm carbide endmill to surface my aluminum bed. Might be able to use 1/2".

HankMcSpank
08-09-2013, 02:53 PM
The thing is about using a large end mill to level the machine bed, I'd rather not have a machine bed with a finish akin to this...

http://hostmypicture.com/images/table.jpg

& also a flycutter should be able to level the whole bed due to it's longer 'reach' (larger cutting diameter) ....rather than having a 'rectangle cut into the bed (which is what happened with my last machine when I used a 6mm endmill) ....but like I say, I'm curious what spindle everyone uses (btw, what's the slowest a water cooled spindle can spin?)

Jonathan
08-09-2013, 03:02 PM
The thing is about using a large end mill to level the machine bed, I'd rather not have a machine bed with a finish akin to this...

Why not? So long as you're spindle is properly trammed it's only an aesthetic problem, which should be last on the list of priorities.


(btw, what's the slowest a water cooled spindle can spin?)

Well it'll spin at a few hundred rpm, but it has virtually zero power available at that speed. The spindle torque (on a good drive) is approximately constant over the whole rpm range. The problem is power is torque multiplied by angular velocity, so as you reduce the speed the power reduces proportionately.

m.marino
08-09-2013, 05:53 PM
What I use is this:

Wealden Tool Company Limited Bottom Trim (http://www.wealdentool.com/acatalog/Online_Catalogue_Bottom_Trim_249.html)

I am using a Kress 1050 and normally surfacing at 2.8 to 3.2m/min feed rate. With my new dust shoe all I get is a fine dust laying on the surface and the shop vac picks that up no problem. I have a 12 to 20 mm MDF board on top (I don't cringe every time I might gouge the surface as I did with the HDPE and the MDF is cheaper). Right now setting up a Vac table and system using stuff I have learned from watching others.

I get a really nice surface and normally only take about 0.1mm to max of 0.25mm and that give me a nice flat surface again. Just IF surfacing a piece of work make darn sure that the hold downs are not in the way of the bit, they are a touch expensive.

-Michael

Jonathan
08-09-2013, 05:57 PM
When I had an MDF bed I just used a cheap 22mm router bit and ran it at 8m/min with the dust extraction. Works well.