End Mill Clarification Question

[wrkwatchr]

Even though I have had my Bot for a while, I am just now getting time to start giving it a proper workout. As part of that effort, I have been searching for some new bits to add to my collection and came up with what is probably a dumb question - but here goes anyway....

As I searched through several vendor websites for "Endmills" including Osrud, Centurion, and others, I noted that most if not all appear to be designed for metals - both ferrous and nonferrous. Virtually none appear to be designed for wood/composites. Are standard solid carbide endmills - upcut/downcut/compression/finish/rough/etc. usable with the bot and wood/wood based products or should I shy away from all endmills not specifically referencing wood? If they are wood-friendly, are there any rules of thumb or do/don't? Any insight would be appreciated.

Roy

[bleeth]

Roy:

The end mills at Centurian and many of the endmills by Onsrud are designed for wood and used by many of us. Other woodcutting endmills are made by Whiteside. There are also many other manufacturers. Get an Onsrud catologue and you will find tons of information about what bits to use for what in there. Check for a SB camp in your area and find out if the Onsrud rep will be there giving a presentation. They often do. They likely also have a rep assigned to your geographical area and if you contact him through their customer service he will gladly be very helpful.

Compression bits are really made for wood as their whole design is so when you cut through the wood the bottom part of the bit (which is upcut while the top is downcut) does minimul splintering.

Glad you're going to put your mill to use-you will have fun learning the ins and outs.

[garyb]

Roy
if you bring up the Onsrud catalog you will find the tooling is categorized into the material types
Eg: softwood,hardwood, mdf, laminated, soft and hard plywoods then your plastics, composite and metal tooling.
You will also find them listed the same way as the catalog on our website
http://beckwithdecor.com/index_files/Onsrud.htm
Gary

[wrkwatchr]

Thanks for the link, but for those sites without such clarification can normal endmills be used w wood?

R

[bleeth]

Yes-The geometry of a down-cutting wood bit is pretty close to a metal cutting bit and as far as it goes if you want to stick to downcutters you can get some very good endmills at decent prices. It's when you start getting into maximizing both the quality and speed of cutting hardwoods, mdf, plywood, melamine, etc. that you start realizing that in some cases more sophisticated bit geometry that is tailored to the particular use is a desirable investment. Do some of the research suggested, do some cutting, and decide if you are happy with the results. If you need more help, come on back with details of the project and you will get it.
As a starter, for Shop-bots, when it comes to bits for wood the 2 flutes are typically the right selection.
Reading the following doc by Steve Glassel may give you some help too:

https://docs.google.com/open?id=0B8GtiBWUjRyRY01lYmNrWW5CVUU

[Brady Watson]

Aside from some very small differences in the tips between them, end mills & 2-flute spiral upcut router bits are identical. If you hold up an upcut spiral router bit to a quality carbide end mill, you will immediately see they have the same helical grind to them. For most operations they are identical, although I prefer end mills because they are truly center cutting. End mills are also much cheaper, even though the carbide in a quality end mill is usually finer than that of a router bit. Don't cheese out buying bargain bits. Quality tools make a difference. Avoid high speed steel (HSS) unless you are cutting certain metals like AL where toughness matters.

You're going to want a few different geometries for most things:

1) Upcut spiral or End mill (ObergBrothers.net, Harvey Tool, OSG, SGS, Micro100, Onsrud)
2) Downcut spiral or 'left hand' end mill (Harvey Tool, OSG etc)
3) Straight flute router bit - (OSG, Centurion, Onsrud, Amana, Onsrud etc)
4) Spiral-O bit (single or 2,3 flute) (HarveyTool, Onsrud etc)
5) Form Cutters V-bits etc - Amana, Freud, Onsrud etc
6) Ball end mills for 3D (same as #1)

When in doubt...try a tool out & see if it works for YOUR application.


-B

[wrkwatchr]

Thanks Guys,

That answers my questions. As I indicated, it sounded like a dumb question but I thought it was worth asking. As you guys all stated (in so many words) when going for the money cut - don't scrimp and use the best available within your budget. I still consider myself a new user, even though I have had my PRT Alpha for quite a while collecting dust, and anything else that could be stacked on it, I am finally getting time to learn the ropes. In this application saving a few bucks makes some sense and I am sure I will learn in short order what works for teh applications I end up doing repeatedly.

Thanks a bunch.

Roy

[garyb]

Contrary to what I've read, there is quite a difference in tooling geometries for materials being cut.
From the helix to the rake and clearance angles and flute geometry.
Helix angle typically run from 20° to 30° (metal to wood)
metal tooling will have low to no rake with low clearance
wood will have medium rakes and high clearance and plastic tooling has high rake to low clearance.

Since these configurations are pre-engineered and tested, you don't have to get too excited about it, but its good to have an understanding of the difference between tool geometries.
This is the main reason tooling is separated into material category's

There is informational/technical documents over on the Onsrud website then Steve Glassel did a excellent job of assembling a PDF doc with a lot of this information here in on the Shopbot forum
Gary

[khaos]

ObergBrothers.net :D

The best is not always the most expensive.

Also I have used Whiteside bits they hold an edge well and are slightly high but available on the shelf where I live. If you have the time to order online or on the phone any one of the vendors in Brady's post are ideal.

fwiw,