"Routing" cast iron.

[dickm]

Not sure if this is the right place for such a query, but has anyone tried using a router on its slowest speed to make a recess in (soft) cast iron? I've just picked up a Ryobi router table, and the section where the router sits is about 17mm thick, which restricts the projection of cutters from my Elu 177. So I want to mill/rout out a recess to take the router base, leaving a thickness of about 8mm. Local engineering shop reckons about £50 to do the bulk of the milling, leaving me to finish the edges.
But I was wondering what would happen with a small TCT cutter at lowest speed to do the whole job?
Any thoughts?
(Don't suggest extension collets as an alternative to a recess - I've had bad experience with them )

 

[johnnyb]

dont do it 8000 rpm is way to fast for ci. even if it wasnt freehand milling of c i is definitely a no no. small ci milling jobs (facing guides etc) can be carried out with a mill vice on a quality drill press. but i fear this would not apply in your case. it is machined dry(without coolant) btw. and is reasonably easy to machine.

 

[jasonB]

Even if you mounted a 1/4" end mill or slot drill in the collet you would not want much over 600rpm so using the router is a no-no. If you were the other end of the country then I could put it on my milling machine

Jason

 

[Chris Knight]

Dick,

I suppose it might be done with abrasives - think die grinder for example. However, I suspect that to remove that much metal would change the stress patterns in the material and leave you with a severely warped table.

 

[devonwoody]

No knowledge or experience but would a dimmer switch bring down the rpm?
Or would a dimmer switch even work with a router?

 

[tnimble]

No knowledge or experience but would a dimmer switch bring down the rpm?
Or would a dimmer switch even work with a router?

A dimmer that is suited for inductive loads can. However the router motor and especially the speed control electronics don't like the dimmer.

Besides lowering the speed you also lower the output power of the router at least by the same amount.

A better way would be as stated to fit a metal milling bit in a drill press. Or use a drill ginrder cone. But no guarenties to the flatness of the table due to material stress release.



Whilst on the subject. Does anybody know the surface speed for milling brass and bronse?

 

[John C]

The metal is only there for a reason probably strength ,if you could machine a rebate the inside corner would need a radius . To prevent a stress crack forming.imho not worth the risk of wrecking the table.
Surely it must be easier to get a collet extension.
One other thing when machining you would release stresses within the casting .i cant think the top will stay flat. cheers John c

 

[ike]

The metal is only there for a reason probably strength ,if you could machine a rebate the inside corner would need a radius

.

No radius necessary.

To prevent a stress crack forming.imho not worth the risk of wrecking the table.

Minimal risk.

Surely it must be easier to get a collet extension.

He's been there (and I have).

One other thing when machining you would release stresses within the casting .i cant think the top will stay flat.

It'll stay flat. :wink:

cheers,

ike

 

[gidon]

(Don't suggest extension collets as an alternative to a recess - I've had bad experience with them )

I'm going to anyway . Only because I've used mine - an Xtreme Xtension in an Elu 177 and it works perfectly (as it does in my current Trend T11). Plus makes changing bits a doddle. A cheap extender in a cheap router gives extenders a bad press - honest this one works very well in decent routers

If you were nearer I'd let you try it out.

Cheers

Gidon

 

[Digit]

I use a home made extension for a particular job, it's in a half inch router and has a quarter inch shanked cutter Loc Tited in it. The shaft was cut to an accurates half inch, fitted into a new half inch collet with quarter inch reamed hole for the cutter.
The total extension is one and half inches and the cutter was the longest I could obtain giving nearly 3 inch depth of cut.
It works very well.
If either shank were worn, or the collet was worn, then I suspect that I would be pushing my luck!
I made my own because of the bad stories I had heard and didn't intend wasting my money on something that wouldn't do the job.
My point is, that well made, and with a good collet, they do work.
Excessive clearance will cause the cutter to run 'planetary' and a broken cutter is probable.

Roy.

 

[jasonB]

Whilst on the subject. Does anybody know the surface speed for milling brass and bronse?

Have a look at these tables, they are easy to follow as they give speeds based on cutter/work diameter and material rather than having to work back from periferal speeds, can be a bit slow to load.

Jason

 

[John C]

Sorry Dickm i missed the bit about bit extension bad experience,cheers John c

 

[tnimble]

Have a look at these tables, they are easy to follow as they give speeds based on cutter/work diameter and material rather than having to work back from periferal speeds, can be a bit slow to load.

Jason

Many thanks

 

[dickm]

Thanks for all the comments, guys. And thanks for the encouragement Ike - you were the inspiration for the idea anyway. As far as I can see, the thickness of metal in the centre of the table is only there to allow for T-slots that take the hold-downs for Ryobi routers. My Elu is bolted in place and would only occupy about half the thickened "island" anyway.
My suspicion was that even the slowest router speed would be miles too high, so you've confirmed that. I've experimented with a proper milling cutter in the Fobco, but it needs a milling table with feedscrew to be feasible.
What I <really> need is an old boy in a brown dust coat with a flat belt drive milling machine in his garden shed that has been there since just before the last war..... But sadly, there aren't many of 'em left

 

[jonny boy]

I've routed aluminium, brass and copper on numerous occasions and if you take very small cuts it's not too bad but when I tried cast iron it's a no-go i'm afraid. The cutter just wont stay firm enough and it tends to bounce off the iron. The best you will achieve is a broken cutter.

cheers,
jon.

 

[Anonymous]

No knowledge or experience but would a dimmer switch bring down the rpm?
Or would a dimmer switch even work with a router?

NOOOOOOOOOOOO!!!!!!!!!!!!!!

Don't even try this.

 

[Anonymous]

Ryobi router table

Cast iron?

Are you sure? I have only seen aluminium ones

if aluminium, then fit an end mil and run at lowest speed and you'll be fine (done this dozens of times).

if cast iron, forget it.

 

[jonny boy]

The Ryobi RT6000 i think!!

 

[dickm]

Cast iron?

Are you sure? I have only seen aluminium ones

Very definitely. The sliding carriage is ally, but the fixed table is nicely ground cast iron. I collected it in the rain, and must have missed a couple of spots on the surface, 'cos by the time it was home, there were neat rust marks there
Anyone want the cheapo Bosch table it replaces?

 

[John C]

Maybe the local tech college could help could be a project for one of the lads on day release.cheers john c