Routering Cast Iron (continued)

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JonnyW

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I posted here a couple of week’s back, on the subject of routering cast iron using a wood bit.

I’ll say here now, I’m a weekend warrior. Joinery used to be my trade once upon a time, but now I spend my working life sitting at an office desk. Woodworking is still my number one passion, however please bear with me if I use the wrong terminology, or cringworthy practices!

As per my original post, my Scheppach Precisa 4 saw has a most irritating mitre track. It’s an inverted T (for want of a better description) that has a 10.5mm opening at the top, and can’t take any (19mm or ¾ inch) stock or aftermarket mitre gauges or mitre track runners. Which is a pest, as I was given a tenon jig for Christmas a couple of years back, which I had to butcher and add a home-made aluminium mitre track. I would love the Incra mitre gauge, but again, I’d have to butcher the thing and add my own mitre track.

I love the saw as it ticks all the boxes – more boxes than I’ll ever need. It can also take a dado blade, or a groove cutter (two blades with various sized shims).
I bought the micro adjuster for the fence, and the side table on the right – it came with the rear take-off table. I didn’t care for the sliding table saw attachment – a bit overly and a budget killer. So I made the folding side table you can see, using the same attachment holes and two very heavy duty folding brackets. It’s very handy when running through larger stock on your own.

So why bother altering such a nice saw? I don’t know really, other than it annoys me. And that it limits third party attachments I can buy for the thing in the future. And also that Scheppach uses such a stupid track design on their table saws. I have a Scheppach bandsaw, and it has a standard 19mm track. And to rub salt into the irritation, the mitre gauge that came with the saw, is slacker than the…… (hmm, that analogy is not for this forum). Anyway you get the picture. A few ugly dunts of a nail punch on its edge sorted it – for a short while.

I’ve had the saw a couple of years now, and wondered how or if there’s a way that I could alter the track, or if it could be altered. I thought about taking it to a local metal shop, but man what a lot of work taking the thing apart.

So I googled routering cast iron, and a couple of videos came up. One was posted as a reply on my first post (thank you for that!). Very interesting, and looked easy enough, so I thought I’d give it a try.

I did a test run in an area that wouldn’t bother me if it went the shape of the pear.

It cut easier than some woods I’ve routered, although as you can see from the photos, it isn’t a large area of metal I was taking away. However, I recon I could’ve routered the full depth no problem – one mm at a time. I recon I could’ve added a lovely moulding if I wanted to!

The fished job came up pretty damned good, and I was very happy with it. I’ve added a series of photos, if you’re interested.

The only thing I would've done diferently, would be to set up my extractor for the metal chippings and place some dust sheets on the floor. Man what a pain trying to sweep and scrub oily filings off a light grey floor! That was the hardest thing about the whole procedure.

Jonny
 

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Great job, well done. Cast iron is very soft and with the carbon content is self lubricating when cut. I’d never have thought of using a router, brilliant result.
 
Glad it turned out well!

I think the key here is that you did your research and you were sensible in what you were doing, setting up a good guide, taking a very cut, taking your time.

I wonder if you could have used a bearing guided bit to do the final clean up pass?
 
You know, now that you mention that, I wish I'd used a bearing guide on the final pass on one side. Why didn’t I think of that – duh. So obvious now.

The track opens to 21mm at the bottom (again Scheppach, why?!), so I had to leave a little metal on one side to keep it at a standard 19mm. I think it was 19.5mm after my final pass to be precise.
 
You'll have nightmares now for the next month about how badly it could have gone. You'll wake up in hot sweats. Hell, maybe this is just a dream, and in the real world it went horribly wrong. You should probably pinch yourself just to check.
 
Ha ha ha ha.

I'll be honest, my heart was racing before that first pass, hence my tester was on the right hand track at the back of the saw where I 'might' not notice an absolute cluster f**k of an idea.

I fully expected bits of router and router bit to become airborne.
 
I must say I'm very pleased that you got such a good result without any personal harm. It's quite true what someone said above about cast iron being pretty "soft" and a bit self-lubricating too, but as someone said in reply to your original post, CI can also have hard inclusions (and sometimes air bubbles) too. It generally machines (lathe) very nicely though, but a router?????????

I'm still wincing to myself every time I picture that wizzing router bit (what's the slowest they ever go down to, 10,000 rpm) first coming into contact with that slab of CI (even just a mm) and the thought still brings me out in a cold sweat every time!

BUT you were obviously very sensible, did your research thoroughly, AND approached the actual job very sensibly and safely, in small increments, so well done you.

But I'm still wincing and hiding under the table every time I think about it (as I said in other post, I AM a devout coward though)!
 
I took the safety part pretty seriously - it did make me nervous. I had double eye protection on (glasses and a full-face mask); leather motorbike gloves and my leather motorbike jacket on (I did consider my motorbike helmet - I jest you not). I was expecting part of the bit to sheer off and go flying.

The router bit sparked away every now and again. Didn't stress the motor one bit, nor the bit. I was very surprised.

I've possibly been lucky.
 
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