Non-standard use of woodworking table saw

1. Don’t try this at home (else really at your risk): metal cutting.

I recently finished making a crosscut sled for my home-made woodworking table saw; the final operation was to mount the sled onto the saw in order to cut its own clearance slot for the sawblade. I accidentally found that some idiot had assembled the sled with a woodscrew in the line of the blade: there was a sudden minor shower of sparks, remarkably little mechanical resistance, and the screw was very quickly and neatly sectioned! After digging out the remains, a part of the screw is shown in the middle of the picture below. The screw is a ‘Torx-Fast’ part from Toolstation, and is expected to be reasonably hard.

I was surprised to find no obvious damage to the (fairly expensive) sawblade. It has 80 carbide-tipped teeth, 250mm diameter, spinning at nominally 4350rpm. So approximately 5800 teeth per second at a surface speed of 205km/hr, or 128mph. The cutter speed of over 11,000 feet per minute is rather faster than I normally use for steel! Something had to give way; I am glad it was the screw.

Whilst I ‘got away with it’ this time, I would not recommend using one’s best sawblade for cutting steel, but it might be worth considering for softer metals? I think the very high cutting speed is probably critical for this use.

2. Do try this at home: plastic cutting

I tried using the table saw to cut some pieces of Perspex (acrylic plastic). I was impressed by the quality of the cut surface: remarkably smooth, with a modest level of the expected scoring from the sawblade but otherwise a partially burnished surface, with no sign of melting, or any significant chipping on break-out. It might actually help that I have some unwanted wobble on the blade: the 3.2mm blade tips cut a 4.0mm kerf. For my intended purpose, it was completely unnecessary to further clean up the surface. In future I shall probably use the table saw to cut Perspex, in preference to a hacksaw.

I understand that plastics are generally cut slowly to avoid melting. However it does appear that if you cut them with a VERY FAST sharp cutter, this also avoids melting, except probably on a microscopic scale at the surface, and gives a good finish on the cut edge.

Martin

PS I have found the crosscut sled to be a very useful accessory indeed, for the table saw.

I've cut 1/8 - 3/16" Aluminum alloy plate on my table saw (regular cross-cut carbide blade) on a number of occasions without any problems - although it's a bit noisy. Need to feed slowly (probably obvious) and normal precautions: eye protection, blade guard down etc.

The speed is probably still a bit fast even for aluminum but it's do-able. I wonder if anyone has tried it with a VFD to get some control over the speed.

Also done Acrylic with no particular problem (although the hardware/lumber stores around here in Canada have recently begun refusing to cut it - don't know their reasoning).

The thing I've never had any luck with is LDPE which is supposed to cut easily. Never does for me.

By way of a side bar I found myself short of T nuts recently and used a woodworking router table to mill some out of a piece of 1" x 3/8" aluminum flat. That worked surprisingly well too, and I also regularly cut 1/4" max steel flats up to 4" wide on my Evolution chop saw.

Metal fastenings are clearly often used in carpentry/joinery. Aluminium star dowels have been used for years to stabilise joints, simply because they are easily machined, whether cutting, planing, routing, etc without damaging the cutters. In the past, and likely still a problem with some hardwoods, was machinery coming into contact with steel jacketed bullets. HSS cutters do not fare well against these unexpected items. Metal detectors were often fitted to installations to avoid such damage - and probably still are.

I have found the same thing happens with nails in pallets. I have a 10" mitre saw and a Screwfix brand TCT saw blade that I use for chopping up pallets for firewood (amongst other things) and staples/nails are frequently hidden in the timber. The blade is almost as sharp now as it was when I fitted it 3 years ago. The original blade had to be replaced when it was down to 10% of its tct tips left. That was a B&Q own brand blade & nowhere near as good.

Where I work we make boxes for expensive stuff (satellites being on the list in the past). Due to the fact many of the boxes go on aeroplanes, we have to make them fairly light, which mean 6082-T6 aluminium extrusions. However they also big enough to need fork lift pockets. Until we got cnc machined longitudinal extrusions for the boxes, we found the most cost effective way to cut the pocket holes was with a 1.5kW handheld woodworking router using a router blade and a timber template clamped to the extrusion. The speed of cut was phenomenal, as was the noise and velocity of the swarf as it was fired across the workshop. OK, killed the routers fairly fast but each lasted a batch of 50 containers worth. The man-hours saving compared to milling the pockets more than paid for the routers. I suspect that had we used an end mill instead of the router bit, the router would have lasted longer.

Regards

Richard.

In the early years of my career in was involved in manufacturing parts for the launch platform for the seacat missile the main cover plates were cut using a large Watkins router and tungsten carbide cutters. This was before CNC milling and we just followed a pre cut template to profile and mill the aluminium parts. You worked out where to stand to avoid the chippings or proped the guard (piece of perspex ) to stop the chippings going down your collar etc. Not much hse in those early days but it cuts the alloy pretty quickly.

David

Edited By David George 1 on 30/01/2017 09:42:01

When you are cutting metal on the wood saw rub a line of beeswax along the cut line, or a wax crayon. It helps the cut.

Clive

Nobody seems to have mentioned the interesting combination of the shower of metal sparks with the heaps of very fine sawdust these saws produce . . . could save on workshop heating costs

Don't think there's enough energy in them, but you're right, it is one thing to be aware of.

Regards,

Richard.

I've accidentally cut through screws/nails with a hardpoint panel saw before now!

The thing that bothers me most is the combination of sparks and a table saw full of wood dust.

Martin

Aluminium dust can be a problem if you start cutting steel.

Ian S C

Always remember to run without the Local Exhaust Ventilation when attacking steel, the dust bags dont like the sparks and draught much. I know what happens

I had a dewalt 3 phase radial arm saw set up to cut a longish taper on the end of 100 x 50 x 6 aluminium channel.......it was a regular repeat job, and it scared the hell out of me every time......ear defenders, face shield, overalls, gloves, a scarf and finally a welding cap backwards, and still the hot chips always found a chink in my defences.

it scared the hell out of me every time.

Did you use a former to support the channel? Much less dramatic if laid under or over a suitable piece of wood, per eg!

I have regularly used my 10" table saw for cutting aluminum up to 1" thick. It works very well with a triple chip blade made for non ferrous metal. It showers the whole shop in fine chips. I said everything went well until one of the chips fell onto the prongs of an electrical plug that was not inserted fully into the socket.

.

Hopefully not a UK standard 13A plug with partly insulated pins

.... The mind boggles.

MichaelG.