how to sand cast iron miter slots

[smiley65]

i own a axminster ac216ts table saw which has a cast iron top just recently i bought a miter gauge for it only to find out the slots on the table are only 18.60mm not 19mm wide what would be best method of sanding them to make them wider,any good ideas would be welcome

 

[gog64]

When I bought my table saw some years ago, I found that a mitre gauge (bought separately) didn't slide along the slot. In my case, it turned out to be more slight defects, rather than the whole thing being machined wrong. I took a piece of flat metal and wrapped emery cloth around it, added some thin oil and ground away by hand. That took out the high spots (which was my machine's problem), but took some time. If the WHOLE of the slot is 18.6mm, I'd be tempted to buy a mitre gauge that has some adjustment for slop (the more expensive ones do in my experience) and try that instead. I wouldn't fancy trying to accurately grind out the whole thing by hand. One of the people with serious metalworking experience might get to a better answer shortly!

 

[Jones]

Wouldn't it be easier to file down the mitre gauge

 

[Ttrees]

If you really want to...
Make a crosscut sled to make sure both are parallel with each other.
Have a look at anyone making one, note that you'd want a stable material for the runners.

Get some marker to colour in the surface of the edges, so the high spots will get the ink removed.
File and block for sure, could even be rebated to keep it 90 if you liked.

Seems like it would be easier to make a runner to suit instead.
Hope you have some suitable tools like a good engineers square at the very least, if ya don't, then wait till ya do before trying this.

Edit...And I should have added, having a known good straight edge/way of making one to a fine tolerance is a must.
A ruler won't cut the mustard here, as if you look at anyone making a sled, you will see how much the smallest error will jam the sled, so might be a good idea to make sure these are not only parallel in the first place,
but of consistent width, a calipers here, or a tight fitting block to check.

The use of a hand plane here if needing to make straight edge/block for checking width, or file holder, if you can't plane sharp edged flat blocks and lengths, then forget it, sanding blocks on say a belt sander likely won't be accurate to do this sorta thing.
Accurate planing ala David Charlesworth's methods will get you there.

You could devise a way of using one slot for running the file somehow on the other.
i.e don't do one until the other is finished.

Does this now seem easier to make a runner instead?

 

[Sachakins]

Watch this guys mitre repair

 

[Fergie 307]

Don't do it. If you get it wrong you could do a lot of damage. Much better, and I would have thought easier, to machine the gauge.

 

[Chris Hawkins]

Hi Smiley, I have the 254 version and I was interested in what mine were. Firstly, I noted Gog's comment about an adjustable guage. I use an Incra 1000HD, but noted that the minimum slot width is 0.74inch, but that is 18.8mm. That is such a far cry from yours is that I would consider this a manufactering error and ask Axi to replace it - it’s hardly fit for purpose? FWIW just measured mine (just measured left of blade slot) and it is 19.1mm give or take a few hundredths. If mine were 18.6mm I would consider it unusable. Yes, I could and have made my own runners/guage but that is hardly the point.
Regards Chris.

 

[John Hall]

Could’ve used a milling cutter, but it turned out really well…cast iron is quite soft when it comes to machining it

 

[deema]

It sounds very unusual for the slots to be that far out. What are you measuring them with? Is the mitre gauge track imperial 3/4” by any chance? Most decent mitre fence have adjustment for wear In the track, anomalies in track width.

 

[smiley65]

When I bought my table saw some years ago, I found that a mitre gauge (bought separately) didn't slide along the slot. In my case, it turned out to be more slight defects, rather than the whole thing being machined wrong. I took a piece of flat metal and wrapped emery cloth around it, added some thin oil and ground away by hand. That took out the high spots (which was my machine's problem), but took some time. If the WHOLE of the slot is 18.6mm, I'd be tempted to buy a mitre gauge that has some adjustment for slop (the more expensive ones do in my experience) and try that instead. I wouldn't fancy trying to accurately grind out the whole thing by hand. One of the people with serious metalworking experience might get to a better answer shortly!

It sounds very unusual for the slots to be that far out. What are you measuring them with? Is the mitre gauge track imperial 3/4” by any chance? Most decent mitre fence have adjustment for wear In the track, anomalies in track width.

Hi its supposed to be 19mm wide and i measured with calipers

 

[Fergie 307]

Ok if it's that far out I would think a call to the manufacturer is in order. 0.4 error on 19mm is a mahusive error, they ought to be ashamed of themselves and replace it.