Thread: What would cause this ?

I cannot seem to find where I can attach a picture

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Garfield, from your description I assume you're making some type of cabinets (kitchen or wardrobe)?

When I built our built-ins, I just used a circular saw with a long piece of wood which I clamped to the timber as a clamp. The advantage of this system is that the fence was very solid, being clamped on both ends. I think that unless you have a very rigid fence on your benchtop setup, you're going to struggle keeping the stock running across the blade in a straight line. Also, consider the ratio of the fence length vs the stock length. Even with a very solid fence, the greater the ratio, the more you will struggle keeping the stock running parallel with the blade.

edit: just saw your photo.
Given that the bad cut is the short side of a longer piece, were you using a sled/mitre gauge? Trying to push a piece in that orientation against the fence is generally a no-no from a safety point of view, but also as it is very hard not to pivot the stock as it runs past the blade given the massive lever that the stock presents.

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Is your blade really sharp? Melamine can be cut successfully using a Contractors Saw as long as the blade is sharp and the bulk of the material being cut is supported to make pushing through the cut is "easy"

I found that even with a sharp melamine blade and my scribe blade set up on my sliding table saw I too get a tiny amount of chipping. Thinking the cuts through to make sure that the edges that will be seen are on the non chipped side is my answer.

The little chips don't bother me too much to be honest it's more the cuts not being straight and true. It's like the whole blade has bobbled and nearly the width of the saw blade has been chewed out if the straight edge.

I'm not sure how or why this has happened.

You haven't mentioned what blade you're using?

I've had similar problems in the past when I used a too low a tooth count blade. From memory, an 80 tooth blade (10") gave me a wandering cut and when I switched to a 120 toother the problem almost disappeared. Same saw, same operator, same day.

I'm not sure on the physics, but I suspect that the larger gullets mean the teeth can be more easily deflected by the harder melamine, with a follow-on effect.

ie. the slightest 'bobble' (as you put it) in feed is magnified at the cut.

For similar reasons, I don't use a thin kerf blade except when I absolutely need to.

Why not use your track saw? I made a couple of jigs based on Peter Millard & others on YouTube. My very old contractor saw (guessing 50+ year) cannot cut anything that wide.
Cutdown sheets on the floor to manageable sizes then up onto a table & used jigs similar to below to get to final sizes - but glued & screwed jigs as wanted something longer term than double sided tape.
TW P4; DIY crosscut jig [video #280] - YouTube
TW P5; DIY Parallel Guides [video #281] - YouTube

As lance mentioned, your cutting the short side...how are you feeding this through your saw?

If all else fails.... try your best and gap the rest.

Here's another jig to help with crosscutting square with a hand held saw or tracksaw.
Was it only the crosscuts that were wavy or the long sides as well?

The fence, mitre guide and sliding table could be better on the Makita MLT100.

If cabinet dimensions aren't critical, you could straighten and clean up the edges with a router against a clamped on straight edge (or using an edge on an uncut board). This will leave it cleaner than a tracksaw.

I normally use a tracksaw for cutting melamine.

Hi G. I have the Makita jobsite saw too and I don't think you will have much luck cutting sheet goods on it unless you build a big enough crosscut sled and mount it in a bench (is this what you meant when you said work station)? The gaps in the cabinet are easily fixed with some gap filler.