Can cast Iron be routed with wood working tools?

[johnny means]

The title says it all. Is there any machine or tool in a well outfitted shop that can be used to machine cast iron? Specifically I would like to mill an area flat.

[Mike Barney Sr]

No woodworking tools can be used for machining cast iron. While you can cut aluminum with a regular saw blade on a chop saw or table saw (NOT a radial arm saw!) or other soft metals like magnesium or tin, you cannot use a router. As far as machining goes, milling a flat surface is not possible on a milling machine. While it will be close, it will not be close enough. The best way is to grind it. Surface grinding is good but rotary (Blanchard) grinding is best. What needs to be flat?

[Keith Weber]

Yeah, run it through your planer! I'm sure it'll work fine! Just be sure to record the event and post the video here! I'm going to get some popcorn! I'd suggest standing behind something solid (like a concrete wall) when you do it, though.

[Jay Allen]

The biggest problem with machining metal, of any kind, with woodworking tools, is the speed of the cutter....and to some degree the shape of the teeth.
Something like a spiral fluted router bit is very similar to what machinists would call an "end mill". If you could slow it down enough, it would work. It's the same with "cut off" saws. There are very similar units, with saw-type blades, for cutting metal, but the motors run much more slowly.
The next issue is density. Most wood cutting methods can be done "by hand", as in hand-fed into the cutter. Metal, even the easy to machine stuff, takes a much more controlled method. Aside from hand drilling, most metal cutting is done with screw-fed controls. The density of the metal just prevents you from just pushing the cut by hand, you need a mechanical advantage.

So, after all of that...
If you would be willing to invest in a "cross sliding table" (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=390281713752+&item=390281713752)and already had a good floor sized drill press, you could take some light cuts in some easier to machine metals. Aluminum, softer steels and cast iron can all be done.
Also take note that cast iron should be machined "dry" (as in no cutting oil) and that the chips coming off will be similar to "saw dust", not curly or like shavings.

[Chuck Tringo]

I did see an article on building a fly rod in woodcraft and the author used a router table with a flat bit set to take a shallow cut...1/64 or 1/32 inch i believe to cut a relief groove in the bottom of an old block plane, so if you went slow and wore proper protection...it just might work....Perhaps a router rails set up similar to that used to flatten wide boards on a smaller scale. mind you I used to jump from planes for the Army so i am not exactly the most cautious guy to get an opinion from :D

[Chris Fournier]

I wouldn't consider trying what you propose. Even machining aluminum with a router is a pretty hairy procedure. I do a fair bit of machining and I can tell you that the cutting forces are large and require secure setups - the kind of setups that woodworking does not offer.

You would be best off to find a home shop machinist that will take your project on for you. If they can't do it they will likely know someone who can.

Also a typical bamboo rodmakers block plane only has about a .003 groove machined into the bottom of the plane. 1/64" is .0156"!

[Jay Jeffery]

How god are you with an angle grinder?
That's about the only metal working tool for less than a few grand that could do the job.

['Jacques Malan']

Filing is about the only hand technique that will work easily and if you are careful, accurately.

There is also a technique called scraping that are apprently very accurate if you know what you are doing, but I don't know anything about that.

As Jay said, very carefully with an angle grinder and files, using some mechanics blue, it can be done. I once got two surfaces parallel and accurate to within 0.2mm using that technique, and I'm not a metalworker.

[Peter Quinn]

Let me just add NO. Jay said it all. Cutter speed, feed speed, chip load based on above plus depth of cut, proper work hold downs, correct cutter geometry in a size that can be placed in a collet, like a bridgeport vertical mill or such. All these factors must be controlled, and to degrees of precisions that wood milling doesn't require and thus wood working machines don't typically afford.

The best you could do if this is a regular thing is to get one of those mini mill/drill set ups that are available, or perhaps something like the Grizzly WOOD/METAL vertical mill. It sure is a pleasure working wood on a bridgeport, and it opens up a world of possibilities for small scale metal milling and shaping too. My next drill press will be a mini mill for sure.

[george wilson]

Blanchard grinding USED to be the cheapest and least accurate type of grinding available. The old Delta Unisaws with the swirl marks on the top are blanchard ground,and accurate to only about .003".

Cast iron is difficult to machine,and must be machined at low cutting speeds. It is full of carbon,that will dull HSS cutters pretty soon,even at low speeds. When I took a light pass on my large lathe to true up its 18" faceplate,I had to go to 15 RPM,and use carbide in order to not have to change cutters during the job( which is NOT desirable).

[Chris Parks]

No woodworking tools can be used for machining cast iron. While you can cut aluminum with a regular saw blade on a chop saw or table saw (NOT a radial arm saw!) or other soft metals like magnesium or tin, you cannot use a router.

Mike, I have routed aluminium many times with a router with no issue at all, like everything else involving a machine it needs care to do. Most ally's that the average user would encounter are fairly soft in the big scheme of things, indeed softer than some timbers.

[johnny means]

What I have in mind is milling some of the webbing out of a shaper top in order to leave a flat area to mount a router. I realize it would probably be cheap and easy to have a machinist do it ( especially since I share a shop wall with a metal shop), but it's fun to solves problems yourself. Alas, if no one on the Creek has successfully managed it, I probably won't try and be the first.

Unless you think you've got a good idea:D.

[Stephen Cherry]

"I would like to mill an area flat"

I think that we need a little more information. Is that a round part that needs a flat area, a potato chiped table saw top, or what?

Lot's of things are possible with a little improvisation, but it is hard to imagine how to do something without knowing what you are trying to do. That said, machine shops do things all the time, and have the machines to do it whit.

[Chris Parks]

If it looks dangerous it is dangerous - to you. This job can be done (angle grinder) but invariable the under side of cast tops are rough and not level enough to mount a router too. Get it machined and you will have a very good router table top.

[Stephen Cherry]

What I have in mind is milling some of the webbing out of a shaper top in order to leave a flat area to mount a router. I realize it would probably be cheap and easy to have a machinist do it ( especially since I share a shop wall with a metal shop), but it's fun to solves problems yourself. Alas, if no one on the Creek has successfully managed it, I probably won't try and be the first.

Unless you think you've got a good idea:D.

OOPs, just read this.

How about a carbide burr to get most of the material off, then a stone chucked up in the router or better a big drill press to make it flat. The best way would be to ask your machinist friend, who probably has a mill to do just this sort of thing.

[Steve H Graham]

I wouldn't say it's impossible to machine a flat surface on a mill. It's basic and routine operation. A milling machine with a fly cutter leaves a beautiful, mirror-like surface, and other types of cutters leave surfaces that are usually not as pretty, but still very flat.

I wouldn't go near cast iron with woodworking machinery UNLESS I had the patience of Job and were willing to use a sander. On the other hand, a mill is fantastic for precision joinery. It easily does things woodworking machinery does only with great effort. Which is probably why a router costs $100 and a good mill starts at $5000.

[Stephen Pereira]

I think I know what you are talking about..I saved an old cast iron table saw top with the intention of making a router table. the underside of the table top is webbed, cast and unfinished or not machined "flat". The problem you will face is that by the time you machine away enough of the webbing(assuming that you could do it with woodworking tools) there would not be enough material left to mount a router.

You Might be able to do it with your router.. if you have a variable speed router, use a small diameter carbide endmill, and take very light DOC..that is if you have a flat reference surface to work off of AND you could adjust your router DOC to .005 or less. Prolly not worth the effort.

I have a mill..Brideport clone.. it is a wonderfull tool but the learning curve is steep and the tooling is EXPENSIVE.

[Andrew Nemeth]

Here is an outside the box idea. Could you cut the webbing with an angle grinder, pour epoxy or acrylic resin on the underside and then machine the hardened resin flat with a router? You can build a dam with modeling clay to contain the resin to where you would like it. You could even add in a few layers of fiberglass cloth or mat to strengthen up the area if you are concerned about the stiffness of the table buy the cut out.

[Chip Lindley]

What I have in mind is milling some of the webbing out of a shaper top in order to leave a flat area to mount a router. I realize it would probably be cheap and easy to have a machinist do it ( especially since I share a shop wall with a metal shop), but it's fun to solves problems yourself. Alas, if no one on the Creek has successfully managed it, I probably won't try and be the first.

Unless you think you've got a good idea:D.


Johnny, among all the "NOs" here, I would submit one "YES". You might possibly chuck a milling cutter in your drill press, set to it's lowest speed, clamp your shaper table firmly to the DP table, and verrrrry slowly feed the cutter into the cast iron. The DP's depth stop would be used to control depth of cut. Many overlapping cuts would have to be made to remove material where needed. Any inconsistencies in the surface could be shimmed with thin shim stock to level the router with your "router table" surface.

[zayd alle]

Johnny,

I just did this with an old Boice Crane shaper, but I decided to go with a local homeshop machinist. I had him mill a recess for my router lift and I actually used the webbing to support the lift plate. I considered trying it myself and probably could have done a decent job, but seeing the clean cuts and tight fit from the machinist left no doubt I made the right call.

[Josiah Bartlett]

Johnny, among all the "NOs" here, I would submit one "YES". You might possibly chuck a milling cutter in your drill press, set to it's lowest speed, clamp your shaper table firmly to the DP table, and verrrrry slowly feed the cutter into the cast iron. The DP's depth stop would be used to control depth of cut. Many overlapping cuts would have to be made to remove material where needed. Any inconsistencies in the surface could be shimmed with thin shim stock to level the router with your "router table" surface.

WHile that might work I would expect it to shorten the life of the quill bearings a great deal. Drill presses are not designed for the side loads encountered by running an end mill.

[Scott T Smith]

What I have in mind is milling some of the webbing out of a shaper top in order to leave a flat area to mount a router. I realize it would probably be cheap and easy to have a machinist do it ( especially since I share a shop wall with a metal shop), but it's fun to solves problems yourself. Alas, if no one on the Creek has successfully managed it, I probably won't try and be the first.

Unless you think you've got a good idea:D.

If it were me, I think that I would use an angle grinder to remove the bulk of the webbing, and ask the machine shop next door to do the finish work. If you remove the webbing yourself, you can save some $ and also have some sweat equity in the project. Plus, by having the shop do the final work they can put a nice rabbit in the cast iron to securely locate the router.

[Ronald Blue]

Stephans idea of using a carbide burr in the router could work. However they have limited life span so it's hard to say how how many it might take to do the job. I would think a good machinist could do what you need in an hour or less. I hope this project turns out for you. Good luck.

[Steve Ryan]

Here is an outside the box idea. Could you cut the webbing with an angle grinder, pour epoxy or acrylic resin on the underside and then machine the hardened resin flat with a router? You can build a dam with modeling clay to contain the resin to where you would like it. You could even add in a few layers of fiberglass cloth or mat to strengthen up the area if you are concerned about the stiffness of the table buy the cut out.
Not outside the box for some of us. Devcon has a product just for that, and so do others. Also not a problem to rough it out with an angle grinder and finish it with a router. I would use a 3.25 PC variable speed router because of its weight, and a 1/4 shank carbide burr. These burrs are made for high rpm use on metal, taking light cuts. I use them on steel a lot. CI is a bit softer, but more abrasive. Def wear eye protection.
Other thought would be to drill and tap (or whatever) your mounting holes and mount the r base exactly as required and make putty dams and fill with a flowing grade of epoxy up to the router base.

[Chris Fournier]

A drill press is not designed to take the kind of radial loads that this task would deliver unless you had a VERY large DP. The vibration that you would get on your average WWkrs DP would loosen your teeth. Carbide cutters while tough are not impact hardy and your DP vibration with erratic hand feeding will more than likely break several of them if you have the stomach to try this process long enough that is.

What is the router set up that you propose to level the surface? You've go to get around the webs and keep the machined face parallel with the work surface. Flat is no big deal - parallel is a fair bit tougher to achieve.

It's entirely likely that the CI will move an amount once the webbing is removed, a largish hole is drilled into it and the bottom "skin" is machined off. I would be prepared to re-flatten and remachine both surfaces for a truely good router table.

If this job is worth doing then it's worth doing right so that you end up with a table that is useful, not sorta useful or even junk which is a possible outcome with the in shop methods that are being proposed. And of course - safety first.

[Stephen Pereira]

Chris is quite right..flat is one thing parallel is quite another. Chris also correct when he says that the cast iron table might warp or move once the internal stresses inherent in the castings are changed due to machining. It would suck if after all your work you ended up with something unusable.

[Steve Orbine]

The year is 2012. Someone is selling a shaper on Craigslist for $ 25, but there is a big hole cut in the top. A prospective buyer scratches his head and wonders 'what the hell were they thinking?' Also for sale that day- a flat screen TV with toilet paper holder bolted through the screen.

[Andrew Pitonyak]

Also take note that cast iron should be machined "dry" (as in no cutting oil) and that the chips coming off will be similar to "saw dust", not curly or like shavings.
Oh My... I thought (based on reading) that to drill my cast iron saw top I should use something to remove heat. I made my own stuff by mixing roughly one part vegetable oil with four parts water and some dish-washing soap. I used a cobalt bit and this kept the bit at a very reasonable temperature.

So, how badly did I mess up, and, why should I have cut it dry? (trying to learn).

[Chris Parks]

Drilling CI is a straight forward job, no special coolants or drills required. In fact it is one of the nicer ferrous materials to machine or drill but it is abrasive on tools and knocks around machine slides and ways if care is not taken. When you do a lot you can actually taste it, not pleasant. In this case it might be if there is not enough material left to hang the router on it may require a machined sub base attached to the cast iron base to reinforce that area. This is all doable and would end up with a far better job than trying to use the usual five layers of particle board or whatever the trend in Router tops is these days. I have never been impressed with how most router tops are built by most people.

Do not use a drill, any machining or sanding process that places side or lateral loads on a drill press is using the wrong tool for the job as DP's are not designed for lateral loads at all. I have seen those adverts for sanding drums, bad idea.

[Rich Engelhardt]

Do not use a drill, any machining or sanding process that places side or lateral loads on a drill press is using the wrong tool for the job as DP's are not designed for lateral loads at all. I have seen those adverts for sanding drums, bad idea
+1...

I learned that lesson.
Before I knew better, I chucked a 1/4" straight router bit in my DP. After all, it was just a little dado I wanted to make right???

A chuck w/a sharp router bit in it, spinning around like some bizzare "death top" all over the DP table, then the floor, is an excitment most people can do without.
I found out that, for an old fat guy, I was still pretty quick on my feet ;)

On the bright side.....I didn't invest a whole lot in sanding drums for the DP.