milling cast iron with a hand held router

newtoll · Dec 15, 2013

used a wood cutting 2 flute 1/2" straight carbide bit. I was going to use an end mill but thought it would be less grabby. After the first cut i turned the speed up a bit and the cut improved big time. I was taking about .025 cuts with great control. the bit is still good after cutting the iron too. I thought i would go for the 60 to 70 SFPM cutting speed but found it too slow for hand held work. This way to clean up the opening in an Oliver 190 bottom scroll sander. Really surprised at how crude Oliver left it.

simple jig clamped well.

opening to mill the 1/4 x 1/4 rabbit in for a table insert

took about 15 mins to cut to the depth

jack
English machines

DMF_TomB · Dec 15, 2013

i would be interested in the sfpm you thought you were using?
.
i have used hole saws to slot a hole by clamping on a steel plate with a hole already in it to act as a drill bushing guide. hole saw pilot drill is removed as it is not needed. using a variable speed drill it is relatively easy to get 300 rpm.
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as most routers are 10,000 to 30,000 rpm i would be interested to know how you slowed it down to 1000 - 3000 rpm ?? speed control is usually hard to control on a slowed down router. i have cut aluminum before with a router but surface finish was hard to control when hand feeding.

newtoll · Dec 15, 2013

tom
Speeds are guess as i am using a rheostat to control the speeds.4000 rpm for 1/2 cutter word best for me but in the video running about 1000 rpm and not the 600 SFPM i mention. I did no have to sharpen the bit but i did turn the speed up on the last cut and took off about .010.though this rheostat is for motors this size. Its got a knob 1 to 10 and i just used my best guess at the numbers on the dial and what i know by sound. I know what my router sounds like with speed control built in and at it lowest speed is 9000 . I look at it spinning to guide my speed as well. That all said i really used control and milling quality to make my adjustment to the speeds. The chips were not blue or hot hitting my bare arms. I am by no means suggesting any one try it . it just what i did with my limited tools. it was a lot easier than i though it would be. As a note i measured the depth and from corner to corner it with in .003

The cutter is in great shape too after the cut with just a bit of roundinf on the tip.

richard newman · Dec 15, 2013

The guy I bought my wide belt sander from had a Martin table saw that he had routed to take a thin, long Starrett scale It was one of those really thin flexible ones, maybe .020, and about 1/2" wide if I remember correctly. He actually routed a shallow dovetail, and the scale just slid right in. Can't remember if he used carbide or hss, but I don't think he even slowed the router down. I was very impressed.

mjk · Dec 15, 2013

Makita 3HP ?

newtoll · Dec 15, 2013

mjk said:
Makita 3HP ?

Yep. I think i got that one back in the 80s. way before speed control soft start.

jack
English machines

newtoll · Dec 31, 2013

it turned out not bad the insert.

jack
English machines

henrya · Jan 1, 2014

Thanks for showing this - I would never have thought to try it.
Good looking results too.

Ries · Jan 1, 2014

I am still not trying it.
Last time I needed stitches, in about '86, was from a router jumping while I was using it on aluminum. I am happy with my current compliment of body parts, and intend on keeping them. My warranty has expired.

I will, occasionally, rout aluminum-if its clamped down, and I am wearing full safety gear, including, sometimes, welding leathers. But I draw the line at ferrous metals, myself.

stephen thomas · Jan 1, 2014

I hate to admit it, but the "psychic" pain has diminished enough to report: a few months ago I was pattern routing a piece of plywood that was a small/short enough cut that I was merely sitting on it on the SCM roller top saw while guiding the router by hand. 1/2" dia carbide tip bit. Something changed in the sound of the cut but I completed it.

When I got up, it became obvious the part had rotated as it was being cut, and the last 2-1/2" had been in a slight arc, into the top edge of the cast iron roller top surface. About 1/32" deep.

Since the top is the eruro-planed surface it really looks ugly. At least it is in an area at the front corner that the cross-cut fence can cover when used for cross cutting. :rolleyes5:

After getting sort of over being PO'd at myself, I did consider the possibilities the information revealed by the accident may have opened up for portable modification of some CI machine surfaces. Kind of along the lines of the inlaid tape that Richard mentions.

It did not apparently hurt the bit, and the cut quality into the CI is "acceptable".

BTW, Newtoll, nice work as always!

smt

newtoll · Jan 1, 2014

Ries said:
I am still not trying it.
Last time I needed stitches, in about '86, was from a router jumping while I was using it on aluminum. I am happy with my current compliment of body parts, and intend on keeping them. My warranty has expired.

I will, occasionally, rout aluminum-if its clamped down, and I am wearing full safety gear, including, sometimes, welding leathers. But I draw the line at ferrous metals, myself.

Aluminium is the worst. Cast is way easier by 10 fold . the alli gums the cutters and is grabby like hell and i hate the stuff too. Cast iron was a piece of cake to mill and a far cry from humble pie.

I'm not suggesting any one try it. i only do what I feel is not that dangerous. lots of safer ways to do like hire a machine shop or buy a mill.

jack
English machines

starbolin · Jan 4, 2014

I'm with you. Lots of mechanics hack away, every day, on cast iron heads with an air spindle and a rotary file. Yours was a much better setup. Kudos

adama · Jan 8, 2014

I think the light feeds and low radial engagement help too. Certainly all the alu routing i have done has always been edge profile of parts often wider radius cuts, but i always take multiple light passes and use a oil for lube.

Am not overly surprised about the bit being unharmed, cast iron is pretty easy going stuff to cut. has a lot of graphite in it and that helps lube things. One thing i would suggest though is giving the router a good blast through with some compressed air after. There electrics are nothing like as hardened by design to conductive dust as most grinders are.

gwilson · Jan 8, 2014

For being easy stuff to cut,it certainly will soon dull a HSS cutter in the lathe,if you try to take a truing up cut on your face plate at any low speed at all. I always use carbide to get across in 1 cut.

newtoll · Jan 10, 2014

cast skin is hard and full of glass and sand. If my top was not ground already i would have had the same problem. Not all cast is the same. pulley and things like that are not a fine a iron as work surfaces that get milled and tend to have more added to help it ware better. I turn down a v cast pulley for the motor on this and had to use carbide.

Mr Science · Apr 5, 2019

anyone tried this in a router table? seems like it might be a lot safer and offer better control - bit facing up and workpiece facing down ...

Bill D · Apr 5, 2019

Wonder how a grindstone would have been to hog out the iron before a final pass or two with a carbide bit. Grindstone rpm may be the limitation factor. As is throwing hot sparks onto a pile of sawdust.
Bill D.

michiganbuck · Apr 5, 2019

QT OP: [Last time I needed stitches]
Good reason to be more professional about this an buy a small bench mill.

My brother was building a shed. With a board on hes leg he tried to cut it off with a skill saw, so yes cut into his leg.
I think he was 13/14 years old and that was about 50 years ago.. learned to be careful and retire as a pattern maker just last year with all his fingers and toes..

milling cast iron with a hand held router

Aluminum

Diamond

Aluminum

Titanium

Titanium

Aluminum

Aluminum

Titanium

Diamond

Diamond

Aluminum

Stainless

Diamond

Diamond

Aluminum

Plastic

Diamond

Diamond

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