Tool recommendations?

[AndyL]

Hey folks,

Please don't take this as blasphemy... or come after me with

Looking for a tool recommendation, building a fairly typical moving gantry router. Construction is HSS steel (channel and tube). Mostly will be using it for thermoplastics and acrylic. As such, planning to use a rotozip style tool for its 'regular' cutting.

However, I know I'm going to throw some steel plate (1/2" x 6" flatbar usually) at it a few times a month - to cut simple bearing plates and adapters.

Could you guys recommend a more appropriate cutting tool for this type of work? I don't mind building another tool holder to swap tools. Ideally I'd like to be able to dry-cut if possible, but I'm pretty sure I could retrofit a liquid cooling system in relatively easily if needed...

Thoughts / recommendations?

Thanks in advance,

Andy

[dertsap]

how heavy of a router are you building in order to cut steel ? rigidity is a definite must , at the speeds a rotozip runs(20000 -30000rpm ) i couldn t even begin suggesting endmills , those speeds will kill any hss , you definitely need carbibe
on our horizontal for example i am running a job doing pocketing with a 1/2 carb ballnose and a 1/4 carb ballnose at 9500rpm feeding at 110 imp and 99imp on structural steel ,and i wouldn t push it much faster ,or without the heavy flood coolant ,
you may be ok with some coated carb endmills light cuts , heavey feed with a heavy airblast , or your tools will no doubt suffer rapidly from thermal breakdown especially if you try to flood the tool

[joecnc1234]

I ran a $500,000 5 axis router cutting aluminium hydroform dies the chances of cutting steel 0......

[AndyL]

Now call me nuts - but using the correct tool (spindle, drive, whatever you prefer to call it) + the correct bit... One would be able to cut steel no?

Why I'm asking about tools and bits... I realize a rotozip is unlikely to be able to cut steel, but being barely beyond design phase - it's easy to add another tool mount to the design.

[dertsap]

if your using linear rails you should be able to make something rigid enough , a larger scale router with some decent torque and adjustable speed it may be possible , but you will still need to be taking light cuts
i just picked up a router that can go as low as 8500 rpm which is slow enough not to burn out tool if a guy goes about it properly , i can t see it not working if you make a good setup , but if your planning on doing any hogging i'd say forget about it

[AndyL]

Routers actually small - cutting area will only be 12x12, built out of 3" x 1/4" channel. Dual 1" acme's on the x and y (had it lying around...) Still working out Z - partly depends on tool(s). Haven't gone with linear rails - modified version of the skate bearing & angle

Which router did you find that would go down to 8500?

[dertsap]

Originally Posted by AndyL Which router did you find that would go down to 8500?

some china dealey

[in2steam]

Originally Posted by AndyL Hey folks, Looking for a tool recommendation, building a fairly typical moving gantry router. Construction is HSS steel (channel and tube). Mostly will be using it for thermoplastics and acrylic. As such, planning to use a rotozip style tool for its 'regular' cutting. Andy

HSS(high speed steel) thats rather expensive(does it come in tube form?) to building a machine with, I just use it for my tool bits I would consider using a-36 tubing. You will find that anything more then .002 , and you will flex your gantry unless its several inches think, I would either consider another different design or another machine.

chris

[AndyL]

Hollow Structural Section... Chances are if you look around a commercial building you'll see a lot of it used - it is your basic structural steel you may alternatively know it as c-channel, i-beams, angle iron, as well as tubing.

I'd have to sit down to work the math - but in the current design, the bearings should fail long before the gantry flexes. But thanks for your thoughtful reply.

[joecnc1234]

have you ever seen a milling machine before?
ground hardened ways with Meehanite castings at the low end. You think Hollow Structural Section is not going to flex when you put a load on it, now there is a load.

[dertsap]

funny hss normally has a whole other meaning within these forums ,

concidering the stuff is made to hold up concrete buildings and such
how anyone can assume flex is well beyond me , which brings me to question if you ever worked on a milling machine ? ive used a fair amount of structural steel and such to make fixtures in order to to cut large steel parts , and flex or vibration was not an issue
i can take a die grinder and put in a 1/4" endmill and cut weld preps or what have you on steel , its not a magical material , a guy just needs common sense thats all
i would strongly suggest moving away from the skate bearing idea and going with linear rails , for that small of a system they should be cheap enough even if you do ebay

there are a lot of good guys in the forums who will post to help you out to create a good design ,don t get discouraged ,JUST MAKE IT WORK

[AndyL]

Yeah, HSS has various meanings - I'm in construction, I deal with both HSS daily and can use both terms in the same sentence without thought; generally assume others do also. Possibly my fault on that; tho I did mention channel and tube in the original post...

We've got a desktop mill at work; don't find much use for it myself other than the occasional need for very precise drilling. The rest of the time - I've always found it easier/faster to freehand my work (grinder/drill press). However there's a few projects coming up I'm thinking I'd like a more professional/clean look.

Design itself has been designed in consult with a mechanical engineer - discussing deflection with him at lunch (and his reviewing this thread) - to get that .002 deflection on the gantry (haven't mentioned it but it is a pair of 3" channels ~5" apart) would require roughly 8200lbs of force, the bit would shear long before reaching anywhere near that load.

Skate bearing type (not actually using skate bearings - my shop is millwright in nature - i've got lots on the shelf to pick from) we still think would work nicely, also leaves the top of the frame open for mounting of the X axis screws - keeping the slop to a minimum.