Spindle Location Block

Apr26
by Thomas Yoon Chee Tuck on April 26, 2021 at 12:00 am
Posted In: CNC

As the holder for my spindle could be removed so that I could replace it with a laser module holder, or a pen holder, I sometimes found that this arrangement could very often cause inaccuracy issues. This was because the spindle holder could shift position slightly, depending on the clearances between the attachment bolts and the holes. This was especially so for the angular position. This resulted in the spindle tool not being exactly vertical to the work piece.

I found this inaccuracy when I did tramming of the z axis.

In most machinery, in order for the various parts to be matched exactly, the manufacturers would drill accurate holes and drive cylindrical or taper pins between the matching parts so that there would not be any clearances for movement. In my case, the matching part was one of aluminium alloy and another of wood. Wood is soft and of uneven material composition. It would be difficult to drill accurately without drifting, so it would not make much sense to follow the same countermeasures. However, I found that a block of wood, fitted perfectly into a machined pocket of the aluminium alloy part could become an effective stopper for any lateral movement.

That’s what I did.

Having positioned a perfectly fitted block of wood in the aluminium holder pocket, the spindle holder was bolted in place and its position was adjusted for accuracy by tramming the cnc machine. Once accuracy of the spindle was achieved (when the tool was deemed perfectly vertical in relation to the waste board), a set of screws were tightened onto the block of wood through the spindle holder, thus attaching the block of wood to it.

The block of wood thus became part of the spindle holder. Whenever, the spindle holder was removed, it had to be moved a little at a time because of the friction fit. Similarly, when installing the spindle holder, it also needed some amount of pressing in order for it to fit in position. But when everything was fitted in place, the accuracy of the spindle remained perfect.



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Jig Saw Table Resting on Table

Mar26
by Thomas Yoon Chee Tuck on March 26, 2021 at 12:51 am
Posted In: DIY

Some time back, I made a jig saw table. It was fitted with an arm for guiding the blade at the top, supposedly to ensure that the blade would be exactly vertical. The jigsaw machine was fitted underneath the table and secured by cleats. The whole jigsaw table was then clamped in position at one end by my vise, while at another end it would be secured by rawl bolt. During operation, there was a lot of vibration. This was understandable because of the inherent reciprocating action of the blade. This made me quite worried that the whole jigsaw machine might fall off one day while in use because of the vibration working the cleats loose. So I had kept it aside and seldom used it.

Recently, I had a use for a table jigsaw for cutting acrylic sheets, I decided to re-design it. This time, I would rest the whole jigsaw on firm foundation at the bottom while I attach a table on it. The advantage of this design is that the heavy weight item – the jigsaw machine – was actually nested firmly at the bottom. So there is no dropping off. The only item placed at the top was a light-weight table. But the big difference was that in this case, the table was resting on the jigsaw shoe instead of having the whole jigsaw machine hanging from it. So even though the vibration was still there, the table even if worked loose would not fall off. The vibration was also less because the jig-saw machine, the source of the vibration, was secured at the base.

In order to position the inverted jigsaw machine in place, I molded the curved handle of the jigsaw machine with some filler cellulose material after making a former for it. I designed two pieces of vertical structures out of plywood that will enable me to clamp the jigsaw machine at the flat sides. By tightening the horizontal bolt and nut I was able to clamp the machine to maintain its vertical position.

Furthermore the table was now made from a sheet of 2 mm steel plate, which makes more portions of the blade available for cutting. Pieces of 10 mm wood strips was arranged to border the jigsaw shoe. The table assembly was just pressed into the jigsaw shoe and cleated in place. There was no way the table would fall off.

I just had to make sure that the hole at the table was accurately positioned for the blade to stick out.

First, a base of plywood was found. Two holes for securing it to a workshop table was made. The plywood base was secured to the table using my specially made wing nut and studs. Then, an inverted jigsaw machine, covered with plastic sheet was positioned over a rectangular open box containing cellulose filler compound and a mold was made of it. During the molding process, I made sure that the jigsaw shoe which was now facing up was horizontal. Later, two wooden structures were arranged on the plywood base so that the jigsaw machine was able to be clamped in position on it. A steel plate table was then fabricated separately so that it can be placed in position after the jigsaw machine was secured in place.



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