View Full Version : Noob alert - 'Starter for 10' feed rates for MDF
26-05-2009, 11:52 PM
I'm just finishing my cheapskate's CNC build....the last thing I need to kludge is a Dremel tool mount for the Z plane.
I intend designing my own Dremel mount (unless someone has already done this & can supply the G-Code - It's a Dremel 300!).
Today, I had my first trial run with a 3mm endmill in my Dremel, which I'd clamped to the Z plane. Truthfully, it was all information overload, but ultimately I was sh*tting myself that the endmill was going to snap leaving me with it embedded in my cheek! So this got me pondering....
So as not to end up with a shiny 3mm endmill embedded in my cheek, what type of ...
1. Dremel RPM
2. feed rates (mm per minute)
3. Maximum depth per run
.....should I be using, so as not to stress the tool.
This will be with 12mm MDF.
27-05-2009, 01:29 AM
Thanks...I'm using a Dremel, because...
1. I'm unfeasibly tight & happen to have a Dremel sloshing around.
2. At this stage, I only intend cutting 2-3mm Perspex (guitar bits & bobs)
As it goes, I do have a great 6.35mm Trend router - but it makes more noise than a Iron Maiden concert....& I'm trying not to draw attention to myself making things in my unconverted loft (the health & saftey officials would spontaneously combust if they caught whiff of my workshop)..therefore I'll go with...
3. My Dremel is relatively quiet.
I really only need to cut this 12mm MDF as a 'one off' (to make a Dremel holder), then it'll be back to girlie plastic for me.
So, has anyone ever used a 3mm endmill/Dremel combination that can give me some approximate cutting speeds to gun for? I'd rather not have the endmill snap & randomly whizz about the room in search of my flesh. Like I say, even at the slowest speed I got the willies ....perhaps it was just becuase the sight of a power tool precariously clamped to the Z plane, spinning at 10000 rpm while having a table with 12mm wood clamped to it moving around beneath it is new to me, but I had an overpowering urge to cower & stand in the farest corner like a complete wuss (& having urgent pangs to take up used bus ticket collecting instead of doing things that can cause severe loss of blood).
03-06-2009, 02:20 PM
Obvious stuff but nevertheless very good advice... like any machinery its always good to explore the limits safely and know what they are
(its like doing an emergency stop in a hire car... do it soon after hiring so you know what will happen when you have to do it for real - anecdote: hired a car in italy, pulled to the right on really hard braking... good thing i knew that on a mountain pass else I'd have been over the edge!)
04-06-2009, 10:27 AM
Thanks for the info guys.
Whilst I understand the rationale in saying that feed rates will differ between machines (linear screw motor strength, machine setup, spindle motor power etc), I meant removing those particular variants, what feed rate could a user expect to be able to cut at for that particular tool size (3mm shank, 3mm cutter diameter, 3 flute ...with a Dremel).
What I subsequently found was that for that particular piddley little endmill on a dremel, the best I can hope for is about 80mm per minute at a depth of about 2.5mm - SLOW!
I can go deeper & I can go faster...but my goodness, talk about drawing attention to your household ...NOISEVILLE!.
As it goes, just tried with acrylic (perspex)...similar results (ie huge increase in noise if I try to go above thoise feed rates), which was a surprise as I'd have though it'd be a lot easier for the cutter to erhm...cut. Just as a side note...3mm cutter diameter seems a little 'wide' for a simple small cuts through perspex...but I'm thinking if I go much smaller, wouldn't the cutter snap that much easier...any acylic cutters here care to comment on what type endmill they use to cut acrylic? (acylic is where the bulk of my cutting will be)
Anyway, thanks for your help...my next project - an acoustic shroud to encase my CNC machine to allow me to go at much higher cutting speeds without fear of having the enviromental noise protection officers slapping me with an ASBO!
04-06-2009, 12:00 PM
Go for single flute router cutters, The problem is in soft materials there needs to be a space for the chips to exit, Once you get past a certain feed rate that ability disappears.
A single flute cutter has the greatest chip clearance available, cleaner exit = higher speed = less heat.
04-06-2009, 12:29 PM
I like the idea of squirting with WD40...hopefully that'll help with the noise. In the light of what you're experience is, I'll also back off on the depth of cut, but then crank up the feed rate a little.
that's a good tip about the single flute...I figured more = good, but what you say makes sense (that said, most end mills I see on Ebay seem to have 3 or more flutes?)
04-06-2009, 01:06 PM
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Not used this company, just did a search for a decent picture.
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