Sunday, October 28, 2012

Canadian homemade table saw

http://woodgears.ca/dads_shop/homemade_tablesaw.html
Back around 1993, my dad built a wooden table saw to use as a second table saw in his workshop
The key parts of this saw were a function of opportunity. When he originally bought his Felder KFS 36 in 1986, it came with an arbor with a slight wobble to it and a sliding table that wore out prematurely. Felder sent a technician from Austria to replace those parts, but dad kept the old parts, which he eventually used to build another table saw.
The problem with the arbor had been a dent in the flange, which we straightened out with a hand file before the technician even came. But the sliding table had ball bearing balls that ran directly in grooves in the cast iron. These wore into the cast iron relatively quickly, so the table developed some play. Basically, a defective design. The replacement table was a different design. I should add that the Felder KFS 36 was a brand new model at the time, but has long ago been replaced with newer models.

The homemade saw was never meant for "fine woodworking", but more for sizing up materials. This is the saw in 1994, when my dad was working on building a new house. Judging by the amount of sawdust and scraps lying around it, it's clear that the saw was in use at the time. It was probably used a lot for cutting 2x4 studs out of large planks from our sawmill
There was no way to catch the dust coming from this saw, but my dad never believed in dust extraction, so that wasn't an issue.

But in recent years, the saw was mostly used as a spare table. It probably hadn't been powered up in a decade.
While it's handy to have a spare saw to make some cuts while the other table saw is set up for something else, the problem with this saw was that it was never a saw for making finishing cuts. One usually doesn't have any special cuts set up while initially sizing the lumber for a project, so it was just as handy to use the main table saw for that.

The saw has a wooden table, and a part metal part wood rip fence.
An aluminium ruler embedded in the table serves as a scale for setting the rip fence.

A bent metal bolt hooks the fence under the edge of the table for locking it.

The table isn't terribly wide for the size of saw, and the furthest to the right that the fence can securely be locked is only 33 cm (11") from the blade. The only time one needs to rip really wide stock is when working with sheet goods like plywood. My dad never used that much plywood, so there wasn't a need for wide ripping capacity.

The saw is powered by a 3 HP motor. A farmer friend of my dad's was also a rep for a farm equipment supplier, and my dad got the motor through him. A lot of farm machinery has to start under full load, so motors for farm machinery have a very high starting torque. It says "farm duty" on the motor's tag.
You can also see the green hinges under the table (used hinges, of course). These are for a simple "height adjustment".

Here's the table tilted way up so you can better see the workings of the saw.
The blade is completely fixed in place, no tilting arbor.

Depth of cut can be adjusted by propping the front of the table up a bit. It's not a feature my dad ever used. For non-though cuts, it was easier to just use the other table saw. Also, the sliding table doesn't tilt, so there was no depth of cut adjustment for cross cuts.

The sliding table has a considerable range of motion.
It was exactly the same size sliding table as the new one on the Felder KFS 36, so my dad could just take the crosscut fence and table extensions off the Felder and attach them to this one for cross cuts.
The sliding table does have a fair bit of play in it in the middle of its travel, but this saw wasn't meant to be super precise, so it didn't matter that much.

The saw blade has a 40 cm (16") diameter.
Various bits of angle iron welded to a steel plate make up the mount for the arbor.
On Felder table saws, the drive belt is just behind the arbor flange. The motor is mounted very close to the arbor, behind the blade, so that the shaft of the motor is actually behind the blade. This makes for a very compact drive unit for the saw.

On this saw, the large motor is mounted at a considerable distance from the blade.
The belt is a worn out timing belt, flipped inside out so that the smooth side is against the crowned pulleys.

The motor pulley is made out of wood. It's a 1750 RPM motor, so the motor pulley is much larger to get the saw blade to turn at about 3500 RPM.
               

My dad initially had some problems keeping the belt on the saw.
The motor pulley doesn't have much of a crown to it, and you can see by the scuff marks on the motor housing that it had slipped off at some point. A piece of wood between the pulley and motor now prevents the belt from coming off this way.
A problem with flat belts is that they need a lot of tension and quite a bit of precision to track well.
Also, the motor, with its very high starting torque, always causes the belt to slip a little before the blade comes up to speed.

The board that the motor is mounted on can slide back and forth. A bolt underneath that board pulls the motor back for belt tensioning. Flat belts require a fair amount of tension to work.

Two screws allow one end of the board that mounts the motor to be moved side to side. This is for adjusting belt tracking.
Most machines that use flat belts don't have a tracking adjustment. They are made precisely enough to make that unnecessary. But this is a wooden machine using a worn out timing belt as a drive belt, so having a facility to adjust belt tracking helps.

The whole saw is on wheels. Wooden wheels, of course. Galvanized steel plumbing pipes serve as axles. The wheel shown here also has a sort of brake to lock it in place.

               

And here's another view of the saw. I attached a table extension, and the crosscut fence, and stood next to it to give a better sense of scale. You can click this or any other image in the article to get a larger view.
I can't say this saw was a tremendously successful project, seeing that my dad didn't end up using it anymore after a few years. But it's interesting to see what sort of challenges he faced and how he solved them.
The biggest downside I see with this saw is that it doesn't have a way to lower the blade. With the blade sticking 11 cm (4 3/8") up from the table, it's not really a saw that you want to use for anything but the largest pieces of wood.

1 comment:

  1. ....reminds me of my dad....always making things to make other things with, out of whatever was on hand.

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