Thread: Can't get an accurate crosscut using sliding table

Hem

Sounds like your sliding mechanism is not running parallel to the blade. Although I'm not sure the sort of length cut that you get 1mm of runout in. 1mm in a 1m cut is 1/1000 and that gets more difficult to find & correct. Is there any play in the slide?

Start with smaller cuts on scrap and check what is happening as you progress to bigger cuts if the smaller ones are square.

If the smaller ones aren't square you need to go back to the parallel bit

Jamie

Barnsey,

Thanks for the reply.

I am also conviced it is either due to the guid rail attached to the workbence is not parallel, or worse that it has a bend in it.

When I use the sliding table in rip mode and use the scale it is acurrate, eg setting the scale to 500, exactly on both sides give a 500 cut. Which leads me to think that the guide rail must be parrallel.

Things I have tried.
* I made an MDF square 900 x 600 and adjusted the fence so it is square with the blade. But once i start the travel along the guide rail, by the time i get to the end it is out 1mm. I guess it is hard to explain.

I think I am going to just have to spend another weekend trying to get thing square (or not)

The one thing I have found with Triton, you need alot of patience and pine.

Sounds like you are dealing with a dynamic vs static alignment problem.

Your measurement scales are correct for the static case - Rip fence mode where the table is locked down.

If you are moving 1mm sideways when using crosscut mode (dynamic) the only explanation can be the guide rail is not parallel to the saw.

Have you tried resting a straight edge against the saw blade so you have an extended line and then measure from the same part of the sliding table in fore and aft positions square to the straight edge ?

Get this right first then worry about getting the scales to read correct I suggest.

FWIW, I keep on saying I'll get new guide bearings and build a fixed 90deg sliding table as I find I always need a few test cuts to get the 90deg setting back after using the fence in rip mode.

Unfortunately there are a lot of adjustments required to get everything setup just right. So double check the saw is parallel to the standard table (rip fence and mitre slots) before adjusting the sliding table.

Ray,

Thanks for the suggestion. Sounds like a plan.....I will give this a go tonight. I have been doing a similar thing with my MDF straight edge, but not quite the way you suggested.

I saw a post on this site about how to make a dedicted 90deg cross cut setup for the sliding table looks pretty good. Once I sort this drama out I might do the same.

Hem

I have noticed for me that it makes a difference where you push the extension table from.

Whenever I set up the extension table (ET) I first check (without timber) that the ET still slides parallel to the table and blade. This is easy to do by locking the fence on the ET and checking that it aligns with one of the aluminium mitre tracks at the same place at the front and back of the table (I hope that makes sense).

Once I know my table is running parallel, I add the timber and with the blade fully retracted (and no rifing knife), I check that my marked cut will align with the blade. I noticed that depending on where I pushed the table from, it could skew by 1mm. This is especially true the heavier the panel you are cutting.

Only once I am sure the cut will be square, only then do I raise the blade and cut, making sure I push from the same spot where I tested.

This was for 2400x600x25 mdf, which is bloody heavy, and it could skew by 1mm. Anything smaller and lighter would skew less.

When tightened down with the clamps close to each end, my fence has a bend in it! Very slight but enough to give errors. The fix is to place the clamps toward the middle. Can not see any reason for this, but it happens. When truing the fence using an engineer's square it will only contact the inner end of the fence.
When cutting a long piece of timber it is more likely you will use the outer end of the fence.
The curve is with the centre towards the operator.
Maybe you have the same problem -
Cheers

Hi Hem,

I have had the same problem. With the table locked from sliding and the fence parallel with the saw blade everything works fine.

But unlock the table and put the fence 90deg to the blade and as John G has said it all depends on how you push.

I don't think I had this problem until we moved but I can't see what changed.

Just went out the shed to recheck what I was about to say.

What I have noticed is that holding the table and wobbling it, there is play in the WC legs. Even after making sure the legs are locked fully, they look like jelly (especially when table is up against the front stops). Is that what is happening on yours?

Maybe legs bolts have loosened over time. At my old place the WC was frequently stored/unstored. Its now always setup so I can be a lot firmer with the bolts to hold it more secure.

Its something I've been living with but I'll have a better look in the next couple of days.

Zathras,
I just tried using an extended staight edge on the table and the made sure the sliding table was same distance (exactly) when in front and then when it was at the back. Initially it was 1mm out, which was the amount the cut was out.
Now I have another problem: The slider is out by 1mm in the center, this can only mean that the is a bow in the inner track. I also noticed it is easy to get the inner track to flex at the far end, i.e. the end that has the longest bit after the bracket if this makes sense.

I think it is time for plan B: Mini slider extension table for the router stand, and use this to trim the cuts square. I think it would be easier with a router, I have been doing this with a few make-shift jigs square and flush trim router bit.

Thanks for all your help everyone.

PS: I love this site. Finaly found a place i can discuss my issues (well wood working ones anway) and maybe even contribute FWIW

Hi all,

Made a discovery about using the extension table yesterday, and was going to post an informative message, but found this one already, so thought I'd add my two cents worth. (the credit card is blown out so that's all I can afford...)

I needed to cut a large panel for a kitchen cabinet yesterday and made my first cut on the end to ensure it was square. I had the extension in slide mode, with the fence at 90 degrees to the blade. After making the first cut, I checked it with a carpenters square (the big ones). The cut was woeful. Probably worse than Hem's 1mm. (insert favourite expletive here!) I think maybe 2 or 3 degrees. It was about this time I was walking inside and looking in the Carbatec catalogue for a new table saw... Reverting back to the table's normal fence, I re-checked the blade alignment and found it pretty close to spot on. Just in case I spent the next hour or so, making sure it was really accurate.

After this exercise, I lined up the carpenters square against the extension fence and blade again. It was still really bad. Having the square just touching the leading tooth of the blade, there was close to a millimetre gap at the rear! And this was only for the short length between the front and rear of the blade.

Then I made my discovery . I loosened the fence hold down knobs and noticed that there is a fair bit of play in the guide rails for the bolts within the guide track. Remember, in this scenario, the fence is perpendicular to the blade. It's been slid down to the horizontal rail (as you're standing behind it) and the two hold down fittings are both located in this horizontal rail. There's probably about 2-3 mm of fore / aft play between the fence and hold rail. Here was my problem.

Leaving the adjusters loose initially, I again put the square up against the fence and blade. I then just moved the fence inside the rail until the square was lined up perfectly with the blade. This might have meant pushing the fence a mill or so forward on the right side of the rail, and pulling it back a bit at the left extent. Whichever way it was, I was able to have a perfect 90 degrees between the fence and blade. I moved the slide along to double check, and found that everything was the way it should be.

My next cut of the panel, was the proper cut to length. I couldn't afford to get it wrong this time. I lined up the panel with my markings and made the cut. The cut followed the marked line exactly.

Problem solved. Once you realise that there is some play between the rail and the fence, and adjust the fence accordingly, everything works the way it should. As John suggests, I was careful while pushing the slide too, just as an extra piece of insurance.

I hope I didn't confuse with my explanation and I really hope it helps you all.

Regards.

Paul.

That's exactly the reason I intended to make an extra table that is permanently set to 90deg.

Every time I swap back from rip mode I'm stuffing about to get it square again.

Hi Paul,

I had noticed the same thing and made sure the fence was square. Unfortuantely with the same result. I am convinced the inner track of the table is bent.
Time to call Triton, hopefully they can send me out another track.

Hem

As an interim measure I am thinking about buying the Triton sliding extension table. The other option (dreaming now!) is a new saw (Carbatec CT-10HB with add on slider or Jet Super Saw with built in slider).

A general question after reading this discussion- Is the Triton slider a good option if it has to stored after each use? Will I be spending a lot of time re-calibrating each time it is set up and each time I switch from rip to cross-cut? If the floor is not very flat/level I guess it would need to be set up in exactly the same place each time, otherwise more things like the outrigger height would have to be adjusted. I also have some reservations after hearing that the accuracy can be dependant on where or how the table is pushed. Any comments?

Cheers
George

Hi George,

Other than the discovery I made on the weekend regarding the play in the fence, the extension is pretty quick and easy to set up. I'm happy I made the purchase.

The instructions demonstrate the fact that the outboard rail can be on a sloped surface etc, so even if your floor is not completely flat, it only takes a coupla minutes to get the outboard rail in a level and useable position.

For the short time it takes to set up (as opposed to assembling from the box...), I think the extension is a worthwhile investment.

Paul.

I have the extension table and often set up in my garden in front of the shed. The wind blows the sawdust away. The garden is not flat but I seem to be able to get accurate cuts by quickly adjusting the outrigger each time (10 min at the max) I have cut some 50mm thick redgum 2.4 long by 900 wide and that is heavy.