Thread: MDF melamine chip edges

You could try placing a sacrificial board underneath your good piece to support the bottom edge. Use a sharp aluminium blade, and don't try to push it through too fast.

I’ve tried masking tape along the cut lines, and it looks like less chip out or it may be stops chips flying out at you so it appears to be better cut??

Looks like a cleaner line but I won’t say that it’s a solution. I’m still experimenting with it.


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Originally Posted by cjbfisher

You could try placing a sacrificial board underneath your good piece to support the bottom edge. Use a sharp aluminium blade, and don't try to push it through too fast.

I assume you mean a blade that cuts Al rates than a blade made of Al?

Using almost any blade with more teeth helps as does a sacrificial board.

The blades that cut Al usually have a "negative rake" so they tend to scrape away rather than dig into material. Because I tend to cut more Al than wood these days this is my standard blade. Mine is a chinese Bosch branded blade that I paid $69 for some 10 years ago and is still going strong. It has a -5º rake and cuts melamine relatively well but as cjbf says it cuts slowly. Also you need to be aware that negative raked teeth tend to push the workpiece away from the blade and back at you although I have never had a problem with this.

I also have a CMT 100 tooth triple chip blade with a +15º rake which CT sells as a laminate blade and while it does a very neat job on the top of the cut it's not as good on the underside as the negative raked blade.
https://www.carbatec.com.au/blades/c...-and-chipboard

CT also sell this one https://www.carbatec.com.au/blades/c...-fine-cutt-off , specifically for melamine
It appears on the website to have a lower rake (+5º ?) marked on the blade but I can't quite make it out.

CMTs recommended melamine blade uses a -2º rake
https://www.cmtorangetools.com/na-en...sided-melamine
Screen Shot 2019-05-04 at 7.41.29 am.jpg

The best blade for cutting melamine supposedly uses hollow ground teeth but these are very expensive to resharpen.
There are almost as good simpler tooth profile blades that use a Zero rake teeth which do almost as good a job but I have yet to stumble across one.

It's not necessary to have a dedicated melamine blade. You need a quality blade, at least a combination, but the more teeth the better. High ATB or triple chip grind blades are best. No flex or deflection in the fence under load. Project the blade above the table just over half the thickness of the stock, feed the stock through the saw. Once cut flip the stock and complete the cut. Accurate feeding of the stock against the fence is mandatory. I've used this method to very good effect.

It is slow and tedious but you can cut oversized and then trim with a router amd straightedge

Originally Posted by Beardy

It is slow and tedious but you can cut oversized and then trim with a router amd straightedge

Before I got a saw with a scoring blade I used a similar method but rather than a straightedge I setup a jointer fence on a router table and used a compression bit to clean up the edges. It's still an extra operation but it goes quickly once setup.

CompressionBit.jpg

There's a limitation on panel size and careful handling is needed afterwards because the edges are dangerously sharp.

Originally Posted by dmorse

Before I got a saw with a scoring blade I used a similar method but rather than a straightedge I setup a jointer fence on a router table and used a compression bit to clean up the edges. It's still an extra operation but it goes quickly once setup.

CompressionBit.jpg

There's a limitation on panel size and careful handling is needed afterwards because the edges are dangerously sharp.

love your 'safety' fence cover, should be used more often

Originally Posted by Tonto

love your 'safety' fence cover, should be used more often

Safety cover? No, that's a dust shroud!

One table saw only approach is to make a very shallow scoring pass on the face first, with the teeth protruding above the table about 1mm or so. This substantially changes the sheer angle of the tooth as it exits the material, and makes it much less likely to grab and chip the melamine. The cut is then repeated with sufficient blade height to complete the cut. The upper layer of melamine is backed up by the core of the material and this well protected, and the lower layer has already been severed so is not as prone to chipping as the teeth are freely exiting the material at that point.
Home brew zero clearance inserts also help to support the material right to the edge of the cut, and reduce chipping. Taping and zero clearance inserts combined produce a high quality cut also.
Ultimately, anything short of a panel saw with well set up scribing blade or an industrial grade CNC router with sharp compression bits will entail at least doubling the work involved and probably quadrupling the time taken to achieve similar results, with time being taken up in second operations, machine adjustments after each cut etc. Probably the most efficient approach if you can access the gear is to cut oversize and trim to size with a comp bit in a table mounted router with jointer fence.

Common compression bits sizes are 1/2in and 3/8in, with shanks having the same nominal diameters as the cutter. For a jointing operation 1/2in bits are a good choice as they mount readily into a standard 1/2in router collet and you are only trimming about 1mm per pass, but they are rarely used for cutting in commercial CNC systems because of the power needed to feed them into the material. The commercial CNC's favour 3/8in comp bits for cutting because they produce less waste, do not require as much spindle and feed power, and components can be nested closer together on the sheet for higher yeild.

Originally Posted by malb

For a jointing operation 1/2in bits are a good choice... but they are rarely used for cutting in commercial CNC systems because of the power needed to feed them into the material.

Not so. Power is hardly a problem today, even the most basic 3-phase 8x4 CNC has at least 5kw, and I'd imagine every commercial cabinet maker needs to cut material thicker than 19mm at some stage (benchtop substrates, laminate worktops, etc) so a 1/2" compression bit is mandatory.

To the OP's question, I've found that a freshly sharpened blade set about 15mm above the material thickness is pretty much chip-free if you feed slowly and let the blade do the work.

I use Malb's idea, it works every time.

thanks folks, few ideas to try out.

Originally Posted by elanjacobs

Not so. Power is hardly a problem today, even the most basic 3-phase 8x4 CNC has at least 5kw, and I'd imagine every commercial cabinet maker needs to cut material thicker than 19mm at some stage (benchtop substrates, laminate worktops, etc) so a 1/2" compression bit is mandatory.

Elan, I specifically referred to needing higher powers for the feed motors, rather than the spindle motors. I had 4 years running a Procam 8x6, cutting eveything from 3mm through to 38mm substrate, plus a range of plastics and aluminium. Our standard cutting bits were 3/8 compression bits, one tool holder was mounted with a 1/2in cutter when I started there and the boss programmed it one job in the four years that I was there, every other job was cut with 3/8 compressions, so a 1/2in cutter would not seem to be mandatory.

Malbs solution of one shallow scoring cut followed by one deep through cut works well - I’ve been doing it for the last few days with good results.

I get even better results with a cordless circular saw on a track. Same thing, one very shallow cut, then one through cut as deep as I can set the blade.

Also don’t forget that, if you think about the average melamine cabinet, there are very few cuts that need to be chip-free on both sides. Most boards you can hide the bad side.