I'm looking for a bit of an oddity [ as far as I can tell anyway]. I'm looking for a 8" long end mill for facing my spoil board. I'd prefer it to have a ~2" cut width which uses inserts [I'd take w/out inserts if I have to] but must have a shank of not more than 5/8". The only use is to face the spoil board on my machine. I won't be ever using it for cutting anything else.

Also, anyone have a good site to explain Arbors and shell mills etc? Thats one thing I'm not too familar with.

Thnx

Would an extension work? You could get a flycutter or small face mill with a straight weldon shank and buy/make an extension. What kind of a spindle is this going on?

5/8" max shank sounds like a 300HZ spindle with ER25 collets. Am I right? Sounds kind of risky spinning an 8" long cutter at high speed. Lots of flex... we're talking 10 times more flex than the typical long flute end mill. (Cantilevered beam equation... length is cubed)

Checkout KBC Tools they have an excellent catalog, and they describe arbors and shell mills and there uses as well.

I'm looking for a bit of an oddity [ as far as I can tell anyway]. I'm looking for a 8" long end mill for facing my spoil board. I'd prefer it to have a ~2" cut width which uses inserts [I'd take w/out inserts if I have to] but must have a shank of not more than 5/8". The only use is to face the spoil board on my machine. I won't be ever using it for cutting anything else.

Also, anyone have a good site to explain Arbors and shell mills etc? Thats one thing I'm not too familar with.

Thnx

You have a contradiction here. A Spoil Board is by definition a sacrificial surface you put beneath your workpiece that will be cut by the tool passing completely through the workpiece. If you need a special 8 inches long cutter to face the spoil board it will only ever be touched in the future by cutters longer than 8 inches. Which does not seem likely :) .

Now for a serious and, I hope, helpful comment. You say the shank is limited to 5/8"; presumably this is what will fit in your collet system. What you need to make or get made is a long flycutter with a shank maybe 1-1/2" with the end turned down to 5/8". Having a shank 5/8" diameter the whole length will simply not be rigid enough.

Arbors and shell mills. Do you really need to know? I could post some photographs if you want them.

Guy's thanks for taking the time.

Here's the why of what I'm doing.

I'm installing my bed and would like to do some deep/long reach routing to put a type of t slot into the bed. Then I'd like to face the bed off so its flat. This will be done once [hopefully] and shouldn't need to be done again. I've designed my mill so that when I'm doing machining, the parts will be loaded on a pallet of sorts and be removable. The pallet's would be ~4-6" thick. Rarely would I ever have to reach right down to the table surface, if ever. I've also left a bit of room for my expansion to a 5 axis system, which will eat up some of my vertical height as well.

The machine was build for making composite molds and bucks. All for large stuff like car parts, boat and airplane parts.. Anything else I can get to work [aluminum machining etc] is just a bonus.

Another approach I've been thinking about is to shim up my bed so that a standard 6" long tool would reach that deep. I can always remove the shim's later to regain the lost height. This would require shimming the table ~3".

For cutting things like alum plate or thinner parts I plan to use a table which I can install on top of the bed and level to it. This will keep my z axis extended as little as possible and hopefully allow me to do some alum milling as well as the wood and foam that the machine was originally intended for. I've got over 24" of Z travel so doing heavier cutting w/ that all the way extended down is going to probably cause chatter and deflection problems.. [I don't know yet as I've not tried this yet]

My spindle is a 18k 2.2hp w/ an ER25 and a max collet size of 5/8".

I have to admit that my largest weakness when it comes to all this stuff is tooling. I'm not familar with most of it or how it's applied. I've bought most of the book's I can find about this kind of stuff, but most of it assume's you know what or how these tools are used. I've got lots to learn in this area. I think sitting down and talking w/ a machinist for a couple hours would help me more than anything in this area.. [Geof, I do still plan to get out there :)]
Knowing what type of arbor fits what type of shell mill or face mill etc..

I see lots of face mills for sale, but never w/ an arbor and it's a shot in the dark to just buy an arbor with the hopes that a shell or face mill will fit it..

What I'll likely end up doing is buying an extension for the end mill's I have. a Fly cutter might do the job for facing off the bed, but cutting the slot's for the t slots would probably need something smaller? BTW, I'm doing a built up t slot from MDF. I've got a 3/4" sheet which I'll route out 1.25"w x 3/8"d and then lay a 1/2" sheet over this and route out matching slots in it that are 5/8" wide, thru the 1/2 mdf. If that all makes sense.. I may change some of those dim's if I end up buying a proper t slot kit.. otherwise I'll just use my own design.. haven't decided yet..

That makes sense but I do have some comments. (When do I not :) ?).

Your tee slot idea in mdf will have limited strength, mdf is not good in tension. Have you considered threaded inserts? Not the el cheapo ones squished out of cheese with the flange but the type that have a deep screw thread on the outside. I would consider screwing these into a sheet of plywood for the structural aspect and then topping it with 1/2" or 3/4" mdf that is faced to a flat surface.

Regarding face mills, shell mills, etc. I think your spindle may be to low powered to drive a reasonable diameter multi tooth cutter. Why not go for a carbide router bit? You will still need an extended holder but that could simply be a piece of round stock turned down to 5/8" at one end to go in your collet and then bored at the other end for the router bit shank.

Alternatively have you considered making an adapter for your entire spindle assembly to allow it to be mounted several inches lower down?

Geof, I'm glad you take the time to add your suggestions.. we've crossed many a bridge in the past working through issues to find workable solutions to problems that make things like this look like riding a bike....

I have some mis-givings about the MDF t-slots but.. they are only a temporary solution. I plan on buying the proper extruded alum t-slots for the entire mill once it's made some money.. [and I've learned not to ding things up :)] Thats about $5k worth of mat'l so.. it may be a year or so before I buy it. I looked at buying some bind nuts but to do what I wanted, it was insanely expensive.. the threaded in kind would probably be worse still..? I may just use screws and screw down into the bed and forget the t-slots all together. Anyway.. I'll cross that bridge when I get there..

Onsrud has some spoil board finishers, however they are way too short. One thing I wonder about when it comes to extensions is.. how do you insert the tool into the extension and keep it all concentric with the shank of the extension? You'd almost need some type of collet on the end of the extension to hold the tool or something?

Can a person buy ready made tooling extensions?

Here's an extension that might help.
http://www.mlcswoodworking.com/orderstatus/html/smarthtml/pages/router_collet.html

And another.
http://www.amazon.com/Router-Technologies-EX-2080-Professional/dp/B000EXQ2FA

Onsrud makes an extension that uses ER-11 collets, but you'll be limited to 3/8" shank tools. They make bigger ones, but they also have larger shanks. Part# 33-34

...... One thing I wonder about when it comes to extensions is.. how do you insert the tool into the extension and keep it all concentric with the shank of the extension?.....

One way to get the extension as concentric as possible is to finish bore the hole for the cutter with the extension mounted in its holder on the machine. Just grip a little boring tool in a vise.

This is not practical for you I would guess and I think you would simpy have to live with things not being nicely concentric...........but as I typed this a wild idea popped up into my head; even before my morning coffee!

An Outrigger Bearing carrying its own collet holder. I did this once on a small mill. It is possible to get ER25 holders on precision ground 1" dia shanks. Fabricate a bracket that can attach to your spindle housing and have a pair of bearings at the end. You don't need really fancy bearings because you are not worried about long life and any bearing will be more accurate and stable than a long whippy extension.

Actually through a combination of things I think I've found the solution.

Ger21 mentioned Onsrud has accessories which include tool extenders. I never realized they had these so I went looking and sure enough, they are limited to 3/8" but for what I need this should be fine. I only plan on doing this once or twice so.. if I have to use a 3/8" tool [or possibly a fly cutter w/ a turned down shank] so be it.. It will be slow and tedious but who cares.. It's not going to become a daily operation [I hope]

I could even buy the larger ER25 collet variety and get the shank turned down from 3/4 to 5/8. This would allow me to use my current ER25 collets and run a 1/2 spoil board cutter as well..

I'll just make sure to stand waaayy back when it use it :D

I'll just make sure to stand waaayy back when it use it :D

Preferably the next room. ;)

Anyone know where I can get a good deal on some body armour and a riot shield? :D

Anyone know where I can get a good deal on some body armour and a riot shield? :D

I would be scared as well.

8" extension <3/4" dia. running at 18k RPM will turn into a 1 bladed helicopter if a fly farts on it. (shudder)

The nose extension (as mentioned above) or temporary relocate of the router (also mentioned above) are my top picks.

Well.. it won't actually be an 8" extension. I only need ~ 3-4" and I'll use a 1/2" bull nose end mill. The only thing I don't really like about all of this is the edges of the bed where the mill can't reach won't be flat w/ the rest of the table.. not a huge thing.. just more of an anoyance when it comes time to slide stuff off the table.

Making spindle mount extension might work.. but then I'd have to re-tram the spindle each time.. yechk..

A spindle extension might work.. but the cost to get it all machined.. to use it once or twice.. kinda discouraging.. Maybe I should just shim the bed.. hrmm...

Ya think a couple inch extension is gonna cause lots of problems?

I could see that onsrud spoil board finisher on the end of an 8" extension being a bit scary but.. a 6" end mill w/ a 3-4" extension?? or are we taking apples and apples here and no matter how ya look at it, it's scary?

......Making spindle mount extension might work.. but then I'd have to re-tram the spindle each time.. yechk....


Oh don't be such a wimp :) .

A spindle mount extension will work and if you incorporate in the extension, and retrofit on your exsiting mount, provision for tramming the spindle with setscrews or something easy to control. Rather than the "have the bolts slightly loose and tap it every which way with a hammer until it is okay" approach.

You will bless the person who goaded you into doing this the first time you have a big job on your machine that happens to need the spindle mounted high for one portion and then dropped down low to reach a different portion.

wimp! WIMP!!!! why I OUTTAA.... sigh.. I just don't have the energy :)

Ya the spindle extension would work.. I've got all of the tramming stuff [set screws etc] located at the top of the slide.. but I guess it wouldn't hurt to have them down on a spindle mnt as well..

I'll have to think about this one.. there isn't much room for some type of adjustment apparatus.. pluss I don't have time to mess w/ it right now.. too much other stuff to do.. It'll have to wait until I REALLY need it.. I gotta get this sucker working and earning its own keep.. it's just about two years I've been footing the bill for it.. time it footed it's own bill...

Plus I just don't feel like pulling appart my Z axis right now.. [which would be required to re-work the Z axis post for installation of all the grub screws etc..

I think I'll forget planeing my spoil board for now.. project #1 won't require it anyway.. and I'll leave the t-slots for another day..lag bolts are much easier to come by when I need to lock something down to the bed.. simple.. and done.. end of story..
[well.. for now] :D

Or a sacrificial apprentice? (only kidding)

talk about a mean boss eh? .. naa.. I could't afford the comp afterwards..:D