I would cut in 4 passes at 40 - 50 mm /sec with 10 mm cutter in 18 mm thick mdf depending on the size of your project.If your project is big ( size of a door)it is fine but if it has some fancy cutting to do use a slower speed.

I always used a feedrate of 10 mm/sec.
This was clearly too slow and perhaps the reason that my cutters wear out quickly.
I've created a brief summary:

CutterDia.: --Feedrate :--Stepdown :
[mm] :----- --[mm/sec]:--[mm] :

3/--------------/15-20/------/2
4/--------------/15-20/------/2
6/--------------/15-25/------/3-4
10/-------------/40-50/------/6

And put the router at max speed .

I guess I can use the same speed for the V-bits .
For engraving something , 15-20 mm/sec , and
for a cabinetdoor perhaps 40-50 mm / sec ?

I use a chipload formula to help set feed rate and spindle speed. The basic formula is:

ipm / (flutes * RPM) = chipload

chipload * flutes * RPM = ipm

ipm / (flutes * chipload) = RPM

Where ipm = Inches Per Minute move speed, flutes = number of flutes on the cutter, RPM is the RPM setting of the router or spindle, and chipload is the size of the chips.

(I like a chipload of 0.015 for plywood and 0.020 to 0.025 for particle board.)

Examples:

500 ipm / (2 flutes * 10,000 RPM) = 0.025" chipload

0.025 chipload * 2 flutes * 10,000 RPM = 500 ipm

500 ipm / (2 flutes * 0.025 chipload) = 10,000 RPM

...okay, I'll admit it - I like math!

Hey Mike,

I try to follow your reasoning.
1 ipm = 0.42333 mm/sec
1 ips = 25 mm/sec

For a 3 mm cutter I use now a feedrate of 20 mm/sec -> 47.244 ipm.
The calculated speed for the spindle must be :
47. 244 ipm / (2flutes x 0.025) = 944.88 rpm.
If this is correct , then the speed of the router must decrease from max -> min ?:confused::confused:

Bart you need to find that sweet spot and it only comes from trial & error,get some cheap bits and play with them.

I think that it is difficult to give exact values because each MM is a little different.
In anyway, this is an "RPM Chip Load Calculator" which I've found on the Internet.

Bart, you’re right.
But, the most variable doesn’t come from theCNC machine it’s self !
Most variable come within from what you may be cutting ( from wood type to another, mdf to another…) cutter sharpness & quality, cutter flute pattern, depth of cut…etc !
No cnc experience yet, but lots in cutting wood :rolleyes: ….and same rules applies !!
Robert ;)

While I am using a different set up than the Mechmate this is very good information and I am glad that I drop in and learn more each time that I can use in my business to make the machine I am doing more useful. I hope to be able to share back a good bit of the data that I am gathering. The only draw back would be that i am working mainly in metric and a good part of you folks are working in imperial.

Thanks for a wonderful birthday present as the info and links have seriously answered questions and put me on the path to being able to get the most from my machine and improve the quality I get out of it.

Michael

I'm looking for some info on cutting leather, it's about .25 thick. A regular up cut spiral bit won't do the job.... it rags terrible, a straight bit does about the same. I'm thinking maybe a down cut bit (haven't tried it cause I don't have one)........ so what do you guys think?

JR,

I think you will need to cut it as fast as you can. Have you tried an 1/8" bit?

I am not sure about as fast as you can. Have you tried different speeds?

Could you press it between two pieces of sacrificial .25 wooden material? Or glue it to a panel before cutting?

JR,
I have had some success using a compression bit and sandwiching the soft (fabric, leather, PE FOAM, Ethyl-based foam sheets and cardboard) between a sacrificial layer. Sometimes really heavy card stock is enough. Just enough to keep the soft material from catching and ripping.

I wish I had pictures of the leather stuff I engraved and cut last year to show you.

BUt the sandwich and compression bit (3/16 I think?) worked pretty well.

Good luck my friend.

Sean

Thanks guys. I think I will try the compression bit.

Hope someone will find it useful:

http://www.woodweb.com/knowledge_bas...ting_Data.html

Bought a 2" 1/16 Countertop Trim bit and was wondering what feedrate to use.
Came across this site.....inches and mm ...Lekker now we can all make use of it :rolleyes:

http://www.mapal.us/calculators/mill...torMilling.htm

Nice Find Kobus !!

Should come in very useful, I have not been to successful so far in this department.

Cheers
Tony.

Onsrud .25" Downcut Spiral Bit
 

Here is a nice deal on eBay for some onsrud 1/4" downcut router bits.

http://item.mobileweb.ebay.com/viewi...d=320863303394

.25" shank
.875" cutter length
2.5" Overall tool length
Solid Carbide

$7.00 each
FREE SHIPPING!!!! :)

Sorry guys I guess the listing is over. He sold 100 like that..

Then I am glad I seen your post because some of that 100 is on its way to me. Thanks James

I don't think they have all been sold - it appears that the demand may have created a price increase. The same part number by the same supplier is listed in this ad:

http://www.ebay.com/itm/57-270-Onsru...item4ab4f1838e

The two part numbers were

57-270 and
57-281

Whats the difference?

From what I can tell, the only difference appears to be $3 :rolleyes:

Looking at both ads, it appears that the first one was for a 1/4" cutter dia. and the second is for 7/32".

In the ad for the 57-270, the part number MPN 57-281 is listed. I assume a mistake as one is 1/4" and one is 7/32".

I now see that the 57-281 has been readvertised.

http://www.ebay.com/itm/57-281-Onsru...item4ab4fc15d3

I also see that it is not available to Canada!!!

Over the last 3 months, I've bought about 15 saw blades, including a $300 Dado set for $60, and about 30-40 router bits.
All for about 20-25% of retail, or less. Some of the prices have gone up due to demand. Originally they were all auctions, but now seem to be buy it now.
It's hard to pass up $80 bits for $14. :) Even carbide tipped straight bits for $5 are hard to pass up.

I just bought 5 more.