# Routing Aluminum table saw top??



## frostr (Jun 18, 2009)

I want to modify my silly craftsman miter slots to standard 3/4. So , I am contemplating taking a 3/4 inch straight router bit and widen the slots from .650 to .750( 3/4 ) . I am interested in your thoughts on the matter, specifically using the router to widen the aluminum slots."


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## Wizard1500 (Jul 20, 2009)

Hi Bob. I am by no means a pro, but, I would not attempt this with a router. I also have a Craftsman, but if I wanted to do that, I would carry it to a machine shop....jmho.....


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## bobj3 (Jan 17, 2006)

Hi Carl

It's no big deal to use the router bit to mill Alum. it's a nonferrous item.. the Alum.will gull the bit but it's only a very small cut..it's like using the band saw to cut Alum. no big deal..

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Wizard1500 said:


> Hi Bob. I am by no means a pro, but, I would not attempt this with a router. I also have a Craftsman, but if I wanted to do that, I would carry it to a machine shop....jmho.....


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## kp91 (Sep 10, 2004)

Bob,

make sure you take a peek on the underside and see how much meat there is to rout away. EYE protection is a must, a face shield probably isn't a bad idea either.

We cut aluminum diamond plate with circular saws, and the chips get everywhere.


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## curiousgeorge (Nov 6, 2006)

Bob,
Even tho it can be done with a router, I think Carl has the right idea. For safety sake and if you want it done with precision (which it should be), then I would advise taking it to a machine shop. It shouldn't cost that much and you know it is done right.


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## bobj3 (Jan 17, 2006)

Hi Guys

Just a note 

Most small machine shops will not have a big mill to take on a job that size,( two slots) ,it will take a big one and the big shops would not take on that small job..it would be cheaper to buy a new saw..

BJ's Machine Shop ,for 8 years..

http://www.routerforums.com/introductions/16506-new-forum.html#post134618

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## CanuckGal (Nov 26, 2008)

BJ I see in the other post you mentioned a "solid carbide bit". Would this be a spiral bit? Sorry I am still learning about bits and their differences.


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## Wizard1500 (Jul 20, 2009)

That's why I like this forum....you learn something new every day.....


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## bobj3 (Jan 17, 2006)

Hi Deb

Yep that be the one  they will last longer and will stay sharper than most bits plus they will plunge in easy..  the only down fall with them,is 1/2" diam.max..

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CanuckGal said:


> BJ I see in the other post you mentioned a "solid carbide bit". Would this be a spiral bit? Sorry I am still learning about bits and their differences.


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## Hamlin (Dec 25, 2005)

I suggest you double check your miter slots. Also, make sure it's aluminum and not steel or CI. Run a mic through each slot from one end to the other. Craftsmen TS miter slots aren't your typical slots. I do have a craftsmen ts that the slots measure differently at each end. This is why I purchased my Grizzly TS last yr.


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## Old_Chipper (Mar 30, 2009)

Bob, 
I know we all do things, which would be best done by someone better equipped. It may be due “lack of funds, “time” inconvenience and list goes on. I’m as guilty as anyone. For that reason I thought about not responding. But decided to log back on and add my two cents. Thought I might be a little more knowledgeable in this area. I have over 35 yrs experience as a research machinist, tool and die maker and Metal Trades Instructor. I earned BS degrees in Precision Machining and in Construction Technology/ Home building. My Master’s is in education.
While most of what has been said is true; I think you need to really think about this. 
Lets just look at a few facts. 
1. A router is not made to cut any type metal. RPM’s are way, way too high. ( The highest RPM on any of my Milling machines is less than my router’s lowest RPM).
2.	A router bit is made for Wood. The angles (relief, Back.etc) are totally different than on an end mill.
3.	True, there are carbide router bits, but the angles are still for wood. An end mill can be used in a router to cut wood, but the finish is not as good. They weren’t made to be interchanged. You just can’t get a router set to the correct RPM. I won’t even get into feed rates.
4.	Any small machine shop that has Bridgeport mill or similar clone; can setup and mill the slot in less than ½ hour. That’s about $50.00 around here. It is correct that a big shop will charge for stopping their line. Add another 200 plus for that. But there are lots of little shops that would be glad to get the work. Find one that likes woodworking and I bet he/she will do it for less.
5.	I looked at my craftsman table saws they have cast iron tables, but I do understand some models do use other metals. 
If you do decide to try it. Here a few more things to consider!
1.	You will need a sturdy jig, the forces will be a lot higher than wood.
2.	If there is steel anywhere in the cutter path. (bolts, trash in the casting, anything) You gonna wish you were on another planet. If you survive it, plan on buying a new router.
3.	The chips, that get everywhere, are over 500 degrees, so be ready not to jump flinch or react when they go in your ears, hair, arms and they love a shirt collar. 
4.	Finish is also dependent on a lot of factors, one is feed. I haven’t met anyone yet, that can hand feed as constant as a machine. T-slots on expensive TS are hand scraped, to remove cutting marks left by machines. What about coolant? Do you have the kind made for aluminum? 
5.	Lastly the bearing in a router is not made for this, so there will be vibrations, this will also cause a very rough finish.
Just about everyone on this forum talks about safety. It should be the first thing we think about when we plan a project. I don’t like telling anyone not to do something they feel is necessary. But at less think this though before you start on it. 
BE SAFE; BECAREFUL
Sorry this is so long!
Harry


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## SE18 (Apr 6, 2009)

interesting ideas. I probably wouldn't use a router simply b/c it would dull the bit. If you have a dull bit already it would be good to use but the end result might look sloppy.

Incidentally, how can you tell if it is all aluminum, run a magnet thru it?

(You cannot rely on manufacturer specs, I found out, b/c I've seen them change metals and/or alloys out over production runs. I know this from experience.)

Not related to this post but another question. I've not done this but what happens if you run into a steel embedded nail you can't see in some used wood?


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## istracpsboss (Sep 14, 2008)

Old_Chipper said:


> Bob,
> What about coolant? Do you have the kind made for aluminum?
> 
> Harry


That's the easy bit. Milk works well with aluminium!

Another issue is the metallurgy. Aluminium comes in lots of different grades, depending on what it is alloyed with. If the original T-slots were cast rather than machined, the grade for casting does not machine as well as the grades made specifically for machining. If you are using the much less than optimum machining method with a router, this will be even more significant.

Cheers

Peter


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## Hamlin (Dec 25, 2005)

For some reason, Milk and a router doesn't sound like a good combo to me. Any fluid that gets inside the router... The safer bet is to take it to a machine shop. Unless you have a buddy who has a mill and is willing to do it for you. Price wise, you may be best to building a new top for your TS or simply purchase a new one altogether. There is a thread on the forums about building a new top. The point is, stay safe. Old Chipper has already pointed out the truths.


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## AxlMyk (Jun 13, 2006)

SE18 said:


> Not related to this post but another question. I've not done this but what happens if you run into a steel embedded nail you can't see in some used wood?


That's why we use hand held metal detectors. I have a CenTec from Harbor Freight. It has found everything, even small staples.


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## Old_Chipper (Mar 30, 2009)

_"how can you tell if it is all aluminum"_
A magnet is not 100% anymore. Recently they are making some aluminum alloys that will stick to a magnet. Spark test still works, but not many of us know how to do that any more. Could send a sample to a lab, I guess. As for foreign objects in the Aluminum. Only way I can think of is x-ray. We always x-rayed all the materials used in the spacecraft projects. Don’t recall ever finding anything in American produced Alloys. Found everything from watch parts to rebar in the china crap. 

_what happens if you run into a steel embedded nail_
Depends on what you are doing. It will chip or break the bit in any case. ¼ shanks often snap off. HSS will end up with a bent shank.
Harry


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## CanuckGal (Nov 26, 2008)

Ok this may be a bit off the wall, but what about using something like a rotozip with a metal cutting bit? You'd still have to make a jig to guide it to get a smooth cut. And I would still take small cuts. But seems a lot safer then the router.


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## Mike Wingate (Apr 26, 2009)

You can buy aluminium specific router bits. Trend manufacture and sell them. Make a slot template wider as the router and longer than the slot. Screw T-end to it so it fits the TS. The slot template should fit your biggest router guide bush. Cut with a slow RPM and feed. Take only small cuts, 1mm depth. Clamp the I-jig to the table securely. Wear long sleeves a mask and goggles. Shiny silver snow goes everywhere. Go for it!


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## frostr (Jun 18, 2009)

Thanks to all, I think I will call or stop by a local machine shop and see where that leads. I will let you know the outcome.


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## bobj3 (Jan 17, 2006)

Hi Bob

No guts no glory  LOL


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## CanuckGal (Nov 26, 2008)

From Pat Warner's "A Router Outing"


> Don't expect to rout ogees, rabbets and the like into aluminum without adversity. It is possible but has to be done in stages, many stages. I would expect to make 1/4 x 1/4 rabbets, for example, in 5-10 passes! By the 10th you may have spoiled the cutter. Convoluted profiles removing large amounts of stock should be done on a milling machine; routing aluminum should be occasional at best.


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## istracpsboss (Sep 14, 2008)

Mike Wingate said:


> You can buy aluminium specific router bits. Trend manufacture and sell them. Make a slot template wider as the router and longer than the slot. Screw T-end to it so it fits the TS. The slot template should fit your biggest router guide bush. Cut with a slow RPM and feed. Take only small cuts, 1mm depth. Clamp the I-jig to the table securely. Wear long sleeves a mask and goggles. Shiny silver snow goes everywhere. Go for it!


Hi Mike

They make them, but I'd be surprised if the machines they are intended for go at normal router speeds, particularly this size. You'd need coolant and probably no more than about 2000rpm.

Cheers

Peter


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## radios (Sep 30, 2009)

istracpsboss said:


> Hi Mike
> 
> They make them, but I'd be surprised if the machines they are intended for go at normal router speeds, particularly this size. You'd need coolant and probably no more than about 2000rpm.
> 
> ...


 it works ok with light cuts, i've done it, no coolant needed. the problem is aluminum is "sticky" and if the normal feed direction is used, it'll be a bit rough, but can be sanded or scraped smooth. for milling aluminum, a "climb" feed is used, which gives a perfect smooth cut, NEVER try that with a router though!!. as far as being made for cutting aluminum goes, it's not, but i used to make cuts in 1/2" thick aluminum on a table saw, about 100 per day, and the blade held up.. of course, when you first do it, you realize the chips hurt like hell, and you need to wear a leather apron along with your face shield!!.


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