[PyroEvil]

Hi all !

A couple of week ago i finish to build my CNC and start to make some work with it. I fix on it a cheap $20 dremel like rotary tool and try some engraving with this type of cutting tool :

http://www.dewalt.com/us/products/ac...categoryID=871

But i see rapidly then this Dewalt cuting bits don't did the job and the cheap rotary tool not strong enough. I decide to buy a Dewalt cutout tool like this :

http://www.dewalt.com/us/products/to...productID=2750

but from a another trademark. It come with 2flutes general cutting bits and work much better then my previous dremel tool and dewalt bits. I can ajust the speed from 15 000rpm to 30 000rpm on the rotary tool.

But my problem is : I always burn my bits in wood ( 2x4 wood lumber ) or MDF.

Here is my setting :

Router RPM: Slow as possible ... 15 000 rpm ( more speed i put on it , faster the bits come to burn )
FeedRate : i try between 60mm and 90mm per minutes but always burn
EndMill Flutes : 2flutes
EndMill Diameters : 1/8'' and 1/4'' ( 3.2mm and 6.4mm)

I broke my 1/8'' bits at 90mm/min in MDF ( probably too fast , not sure )
And i burn ( not too much but just enough ) my 1/4'' at 60mm/min and 90mm/min in 2x4 pine lumber.

Any body can help me with that please?
I don't know what i need to do .... push higher the FeedRate .... my rotary tools turn too fast ( i see then sherline router turn between 70 and 2800rmp but see a lot of homemade CNC with dewalt like rotary tool) .... or my bits is too cheap.

I planning to buy some 2 or 4 flutes carbide endmill on Ebay but i don't want to buy this for burning it again.

thank and so sorry for my poor english

[ger21]

You need to go at least 1000mm/min, 2000-4000mm/min would be better. You bits are getting too hot from going too slow.

[mcphill]

How deep a cut are you trying to take?

Hi all !

A couple of week ago i finish to build my CNC and start to make some work with it. I fix on it a cheap $20 dremel like rotary tool and try some engraving with this type of cutting tool :

http://www.dewalt.com/us/products/ac...categoryID=871

But i see rapidly then this Dewalt cuting bits don't did the job and the cheap rotary tool not strong enough. I decide to buy a Dewalt cutout tool like this :

http://www.dewalt.com/us/products/to...productID=2750

but from a another trademark. It come with 2flutes general cutting bits and work much better then my previous dremel tool and dewalt bits. I can ajust the speed from 15 000rpm to 30 000rpm on the rotary tool.

But my problem is : I always burn my bits in wood ( 2x4 wood lumber ) or MDF.

Here is my setting :

Router RPM: Slow as possible ... 15 000 rpm ( more speed i put on it , faster the bits come to burn )
FeedRate : i try between 60mm and 90mm per minutes but always burn
EndMill Flutes : 2flutes
EndMill Diameters : 1/8'' and 1/4'' ( 3.2mm and 6.4mm)

I broke my 1/8'' bits at 90mm/min in MDF ( probably too fast , not sure )
And i burn ( not too much but just enough ) my 1/4'' at 60mm/min and 90mm/min in 2x4 pine lumber.

Any body can help me with that please?
I don't know what i need to do .... push higher the FeedRate .... my rotary tools turn too fast ( i see then sherline router turn between 70 and 2800rmp but see a lot of homemade CNC with dewalt like rotary tool) .... or my bits is too cheap.

I planning to buy some 2 or 4 flutes carbide endmill on Ebay but i don't want to buy this for burning it again.

thank and so sorry for my poor english

[PyroEvil]

2-3mm with the 1/8'' and 3-5mm with the 1/4''

How deep a cut are you trying to take?

[widetrack]

I just cut a shopbot engraving on a piece of 24" x 24" x 2" fir with a 60' vee cutter to a depth of 1.125" at 30 ipm and 20k rpm. with nothing close to burning. the only real time I see buring when cutting wood is when the tool does not have enough clearance on the primary land, and wood cutters only need 1 land. what kind of cutters are you using? where did you get them? are they reground?

[PyroEvil]

wow ... it's fast and near from my value.

I set my jog max speed at 800 i think because the Y screw
vibrate at more then that.

And i know then near 2000 my
stepper motor start to go out ( stop and make a buzzing noise ).

I use the HobbyCNC kit but for now I set the amperage of
the stepper at 40% of is maximum ( or something like that ..minimum recommended for test ... my drivers chips and stepper is just a bit warm on touch and i know at it's maximum value it's can go hot enough).

I will try to going near of this feedrate value at the end of the day.
If is the problem , i need to find out how i can stop the Y screw from vibrate.
When i'm feel more secure , i probably crank up the amperage of my stepper to 75% for better performance.
Probably the cheap quality "drywall/general purpose" bits don't help too ( for the burning problem)?

You need to go at least 1000mm/min, 2000-4000mm/min would be better. You bits are getting too hot from going too slow.

[mcphill]

Certainly could be the bit. I think drywall bits plunge the waste material down, so you will be "clogging" the cut with the dust. Get some cheap carbide bits at Home Depot or Lowes - they sell them in kits of 3-5 pieces of varying sizes, usually around $20-30.

wow ... it's fast and near from my value.

I set my jog max speed at 800 i think because the Y screw
vibrate at more then that.

And i know then near 2000 my
stepper motor start to go out ( stop and make a buzzing noise ).

I use the HobbyCNC kit but for now I set the amperage of
the stepper at 40% of is maximum ( or something like that ..minimum recommended for test ... my drivers chips and stepper is just a bit warm on touch and i know at it's maximum value it's can go hot enough).

I will try to going near of this feedrate value at the end of the day.
If is the problem , i need to find out how i can stop the Y screw from vibrate.
When i'm feel more secure , i probably crank up the amperage of my stepper to 75% for better performance.
Probably the cheap quality "drywall/general purpose" bits don't help too ( for the burning problem)?

[PyroEvil]

It's a 2flutes general purpose cutter come with the Cutout rotary tool with flat tip ( not a ballnose ). The cutter are new from the box and never used.
I'm newbies in this domain , my english is not so good but i don't know exactly what you mean about "enough clearance on the primary land".

I just cut a shopbot engraving on a piece of 24" x 24" x 2" fir with a 60' vee cutter to a depth of 1.125" at 30 ipm and 20k rpm. with nothing close to burning. the only real time I see buring when cutting wood is when the tool does not have enough clearance on the primary land, and wood cutters only need 1 land. what kind of cutters are you using? where did you get them? are they reground?

[widetrack]

your english is okay, no problem.
The point is that when i use a sharp router bit, even when i stop the feed or really slow it down, there is no burning if the bit is really sharp, the 'land' is the area on the outside of the bit behind the cutting edge. on bits for wood I like to have a min of 4 degrees of clearance, this way the bit does not rub on the material. if you have a really cheap bit, as it gets dull, the clearance goes away and allows the tool to rub and not cut cleanly. this is where the heat comes from. i have seen some bits that are cylindrical with no clearance behind the edge. There is alot about the geometry of a cutting tool that effects how well it is going to do in certain situations. alot of wood cutters have no radial shear angle, so if it is resharpend wrong it will have a negative shear angle, causing alot of heat. alot of router bits have no spiral, so the chips are not moved up and cleared when pocket milling. if I where cutting this ( and it's just me) I would have a 2 flute high spiral end mill. if the run was long i would use carbide. otherwise I would use cobalt. and clear the chips/dust away. recutting these can dull a cutter fast.

"my english is not so good but i don't know exactly what you mean about "enough clearance on the primary land".

[PyroEvil]

yes, if i remember, you right !
If i check the spiral direction versus the tool rotation direction , it's push the dust down i think.

What kind of carbide bits i'm need to such at HomeDepot? For traditional wood router ? My rotary tools just accept 1/8'' and 1/4'' shank.

Certainly could be the bit. I think drywall bits plunge the waste material down, so you will be "clogging" the cut with the dust. Get some cheap carbide bits at Home Depot or Lowes - they sell them in kits of 3-5 pieces of varying sizes, usually around $20-30.

[ger21]

Yes, look for 1/8" or 1/4" carbide upcut spiral router bits. Both will have 1/4" shanks.

[PyroEvil]

ok thanx !

The bits i planning to buy before posting on the forum is this kind of bits :

http://stores.shop.ebay.ca/BWBTool-C...34Q2ec0Q2em322


Did you think is a good one for the price ?
I know carbide is the best think compare to rapid metal bits.

( i don't know if i can't post this kind of link , sorry if not , i can remove it )

[PyroEvil]

nobody knows if is a good buying ?
for a newbies !

[Montabelli]

the key features you need in your cutter are 1) center cutting, it needs to be able to plunge cut. 2) you want to be able to clear the chip. if you are taking partial cuts ( multiple depth cuts an up shear or spiral will do best. 3) if you are cutting mdf go with carbide, HSS will not last long in mdf.

cutting speed is something you will need to experiment with. too slow and you toast the tool, too fast you break it. if you can't keep it moving with heavier cuts, lighter cuts faster will probably be better.

[PyroEvil]

Thank you all !

I did something yesterday and i find the right speed for my machine without burning my tool. Between 200 and 300 mm/min with my 1/4" endmill is just fine.
More than that my axe start to vibrate. I need to get some piece more stronger.

Thank again !

[PyroEvil]

I thinking about buying ( consider then my tool just take 1/4'' and 1/8'' shank ) :

1/16" TiAlN, 1/8" shank , 2Flutes, Square End, CenterCutting, 1/4" LOC , 1 1/2" AOL
1/8" TiAlN ,1/8" shank , 2Flutes, Square End, CenterCutting, 1/2" LOC , 1 1/2" AOL
1/8" TiAlN ,1/8" shank , 2Flutes, Ball End, CenterCutting, 1/2" LOC , 1 1/2" AOL
1/4" TiAlN ,1/4" shank , 2Flutes, Square End, CenterCutting, 3/4" LOC , 2 1/2" AOL

What are you thinking about my selection for a beginner ? I want it for fun, practice and make my first ArtWork , prototype and furniture in wood. Certainly buy anothers after experiment with this one.

[ger21]

By wood cutting router bits, not metal cutting end mills. They'll be more expensive, but should give better results.

[PyroEvil]

You talking about Freud router bits like this (straight ) ?

http://www.freud.ca/English/Pages/Bi...ubleFlute.html

Or Freud router Spiral bit like this

http://www.freud.ca/English/Pages/Bi...al/Spiral.html

This last one look like exactly the one i plan to buy ( same number of flute and angle of it )

[ger21]

Either one. Router bits are designed to cut wood. Endmills are designed to cut metal. Use the right tool for the job.

[PyroEvil]

okay , thanks again !