MechMate CNC Router Forum

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-   Cutting various materials - bit selection, feeds, speeds (http://www.mechmate.com/forums/forumdisplay.php?f=82)
-   -   Speeds, Feeds, Materials and Bits (http://www.mechmate.com/forums/showthread.php?t=724)

Gerald D Sun 07 December 2008 10:56

Greg, you didn't ask about this, but I'll tell you anyway . . . .

There are 2 "tricks" to eliminate those tide marks when you multipass cut through thick material:

1. Make the initial passes at a slightly bigger offset (away from the finished part) and than do the last pass at the correct offset.

2. Make the initial passes in the climb-cut direction (clockwise around the finished part) and then the last pass conventional cut direction (anti-clockwise around the finished part). The cutter deflection will take away the marks.

Both the above methods take off a small skin from the preceding passes.

gd.marsh Wed 30 September 2009 17:48

Spoilboard Surfacing
 
Just wondering if anyone has used a Safe-t Planer in a router for spoilboard surfacing? I know the router would have to be run at lower speed, but just curious ..

Robert M Wed 30 September 2009 18:51

Hi gd, Few thing comes up to MY mind, when an armature tools is inquired or compared to an appropriate pro tool.
1st, you should be concern by a reality among other facts; it is a substitute of some serious pro tool. This tool market segment is targeted for those lower budget & low usage hobbyist and to be set up on a press drill….not meet for CNCs !
2nd, to bring down a router to this tool operating MAX RPM ( Max 6000 as per Wagner, who own the trade mark) you be losing the router oomph (torque)…that is if you can find a router that can be brought down to 6000 RPM
3rd....think safty.... I'm not sure with this one :eek:

Another reason, that goes without saying it would take an eternity to get a spoil board done !.... MDF is a lot more abrasive than any narrow pieces of some type of solid wood….would those cutters be up to it ??... or a few changes would be needed !?

In my opinion ( also bear in mind I make furniture as a living, so to me, I’m never poor enough to by cheep tools, unless it’s for some single usage…. A throw away kind !)…. I would suggest abandoning the thought of trying this amateur type tool and opt for something like similar to this one !
My 2cts....Amicelement, Robert ;)

Gerald D Wed 30 September 2009 23:12

1 Attachment(s)
gd, I don't see the point of your question. Would you use this cheap tool in a router if someone posts that they have done it before?

The risk of your router being set to the wrong speed, or the speed control malfunctioning is just too great. But you will probably burn the router by loading it at such low speed.

gd.marsh Thu 01 October 2009 07:54

Guess I hadn't thought it all the way through. Saw this thing and the wheels started turning. I'm not a Mech Mate owner, too large & heavy of a machine for my needs. I'm a hobby user just completing a 660 x 1270 machine. However, I have gleaned more useful build information from this site than most others out there. Thanks for the quick reply.

Barman Thu 29 October 2009 03:11

Initially I used a KINZO router 650W with constant velocity 30.000 t / min.
The used cutters were - Black & Decker - HM / TCT - 8 to 10 mm (Piranha).
The used feedrate to cut MDF was 600 mm / min.
My problem is that the mills wear very fast (after hours) . :(

Therefore I did some reading about chiploads and such things , but I dont get out . :confused:
I looked for tables and feedrate calculators .
The recommended spindle speeds and feed rates are too contradictory.

So , I want advice from some specialists .

I've changed the KINZO for a METABO 700W grinder (adjustable speed ) and bought some new mills from CMT.
What is a nice feedrate and spindle speed to cut some MDF ?
Endmills 3 mm - 4 mm - 6 mm - 10 mm?
V-Bit - 19 mm dia - A = 90 °
V-Bit - 12.7 mm dia - A = 60 °

I want to make a puzzle from a 4 mm MDF plate and do some engravings with the V-bits also in MDF (without throwing away the cutters after afterwards ).

Thanks

hennie Thu 29 October 2009 03:55

Bart , I use a 1/4 inch (6.3) mm router bit on 3-4 mm mdf to cut. Use the max speed and run your cutting speed at 15-25 mm/sec.It gives a clean cut and you can cut in one pass.Put some double sided packing tape under the mdf to keep it on the table.

Barman Thu 29 October 2009 04:50

Can I use this feedrate of 25mm/sec also for the 3 mm and 10 mm cutter ?
I've just tried the feedrate (without cutter) and it sounds better than before and is 2,5 x faster.

hennie Thu 29 October 2009 06:31

I would suggest for the 3mm cutter 15-20mm /sec when you cut thin material and the 10 mm dia cutter you would probably use on thicker material.?

Barman Thu 29 October 2009 10:19

Yes , the 10 mm is for cutting mdf of 18 mm thick

hennie Thu 29 October 2009 22:19

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.

Barman Fri 30 October 2009 04:26

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 ?

Richards Fri 30 October 2009 07:52

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

smreish Fri 30 October 2009 12:30

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

Barman Fri 30 October 2009 14:33

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:

hennie Fri 30 October 2009 22:09

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

Barman Sat 31 October 2009 03:08

1 Attachment(s)
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.

Robert M Sat 31 October 2009 04:12

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 ;)

m.marino Sat 26 June 2010 05:27

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

J.R. Hatcher Mon 12 July 2010 13:43

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?

sailfl Mon 12 July 2010 13:48

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?

bradm Mon 12 July 2010 14:49

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

smreish Tue 13 July 2010 05:56

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

J.R. Hatcher Tue 13 July 2010 07:04

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

digger Fri 15 October 2010 16:48

Hope someone will find it useful:

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

Kobus_Joubert Sat 07 January 2012 11:40

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

AuS MaDDoG Sat 07 January 2012 16:52

Nice Find Kobus !!

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

Cheers
Tony.

jessyjames Fri 09 March 2012 05:51

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!!!! :)

jessyjames Fri 09 March 2012 09:09

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

bolingerbe Fri 09 March 2012 12:29

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


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