I do think we should keep a larger bit for clearing. I’d like clearing bits to be up cut for chip evacuation and longevity. Finish with a downcut as necessary…
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Our workhorse bit should be a half inch straight cut plunge.
They are about $20 apiece, remove material quickly and in my experience give a good finish. They can also be resharpened easily to top it all off. I have also cut thick plexiglass with these and it had an accceptable finish. Feel free to experiment with less than a half inch, because I haven’t.
The downcut’s have one major problem, they pack the chips in on deeper cuts, at some point if you are not constantly pausing and clearing the chips, the spindle is not able to clear the chips any more causing the spindle to torque out and trash your part or break the bit. Downcuts should really only be considered for special circumstances where hold down is going to be an issue.
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Very excited to see the plastic bits being added! Thanks Tapper!
I’d like to see the formula for this on our router, i get nothing but dust.
These days I cut MDF at 5-6 ips, 19,000 RPM, with a single flute 3/8 cutter. My chips measure .025-.030" thick. They look very similar to the chips I get from plywood - little scoops/shavings 1/4" long x 1/8" wide, like a mini version of what you get from a block plane.
These chips are easy to contain/collect with the dust shoe and I don’t get a film of dust building up on the rest of my equipment, glasses, etc.
Where is this quoted from? The math doesn’t quite add up, but it isn’t too far off…
360 ipm / (19000 RPM * 1FL) = 0.0189"
Might want to invest in one of these for spoilboard maint
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These are awesome for personal machines, but since it is DMS, I would be worried about someone spinning them past 12k RPM. Doing so is really bad for spindle bearings and could cost us a spindle.
I would also not want to find out what happens if it were to go to 24k rpm.
I would think we would keep this one locked up for supervisor use only for spoilboard maint.
Not readily available to the public…considering its a $250 bit…
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I’m not sure what the max diameter bit is that will fit in the dust boot. The bit we use to surface (unless it’s changed) is only 1.500".
Nothing wrong with .5 bits, but they just aren’t used very often. By far and away, .25 bits are the go to bits in our shop, and I would estimate that roughly 70% of the inches cut are plywood. This is why we want to add compression bits, which are superior in all ways for plywood cutting. At 1 CED, a .25 compression bit runs at about 80-85% of maximum gantry speed, while producing far less dust load, and producing a superior finish at higher detail. Larger bits can easily max out our gantry (600IPM).
One of the principal objectives of this work, apart from saving money and improving bit sharpness, is to re-vamp the tool library using feeds and speeds more appropriate for our bits. The currently loaded values tend to be very conservative, and this is one reason why bits are getting so dull or breaking. These bits are designed to run at a relatively narrow range of F&S, and getting too low (or too high) causes damage to the bits.
Bits running too slow produce copious amounts of dust, instead of chips. This not only damages the bit, it loads up our air conditioner, air filters, and dust collector filters with fine particulate dust, which is even more dangerous to people than it is for machines.
We as a group, need to watch for this - if a user is making dust, stop him, and assist him in modifying his F&S to eliminate the dust.
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Well i need help all i create is dust…MDF is straight forward, i wouldn’t mind a MDF library with the 1/2, 1/4 and 1/8 set at at the proper speed/feed rates, to create the correct chipload.
I attempted to do a few calculations and the feed rate seemed a little slow in the library current, which may be why all i create is dust. What would be helpfulis maybe a reference guide in the tool box with a common chipload for the tools that we have similar to the laser materials guide for power and speed, and maybe give a training on how to calculate this based on your material. I think the training stops at safety and doesn’t go into the science of how the CNC and the bits needs to work with your material.
Maybe even add a calculator link to the desktop. I see alot of people talking about feeds and speeds, but then nothing is being done to make sure the users understand the chipload concept as well.
The current library is set to conservative, and new users are gonna use that. So if we are gonna look into preserving bits then there needs to be training on this aspect of the machine.
The thunderlaser requires you to know power and feed, the only drawback is you dont mess up the machine you mess up your material. On the CNC side, the configurations dont really screw up your work, just the bits. Users at that point at so excited that its cutting and dont really look at the impact of incorrect feeds and speeds.
THe super users are a handful, the regular users are many, so thats where the bit preservation is gonna be a problem, if you dont get that science across to them, we are gonna have this discussion every quarter.
Most of the available calculators, for example CNC Wizard, produce F&S that are too low for wood on the router.
What about creating a materials F/S list then? Similar to what the laser has.
Our list should be that long, if you’ll help me, i’d like to to the MDF list, and the birch.
Think that’s pretty much what we’re doing by Modding the tool library, and the F&S varies by bit type, bit size, number of flutes, material, and cutting depth - so a lot of info to process to arrive at the correct speeds.
I think MDF might be one of the first that needs to be done, as it has the worst affect on the woodshop.
Please keep that .20 engrave bit; I use it pretty regularly.
why are these needed? The general feeling I got from discussion [Expanding the use of the CNC router] (Expanding the use of the CNC router)
was that the cnc watchers didn’t want plastics done on their CNC -otherwise my proposal should have been a no brainer. Given that - NIX these.
I think a big part of that was the shared collection system. Mixing plastic in with the sawdust, etc. Isn’t the multicam getting it’s own unit and hence plastic becomes much less of an issue?