miniature table saw with adjustable cutting height

[bmandl]

Hello guys. Few days ago, I started my first electronic enclosure design for 3d printing. I have never tried to design one before and I got so exited, that I ordered my own 3d printer Now, since I will have a chance to print my own models, I was thinking that I could make something useful. So I came to an idea, what if I build my own miniature table saw for pcb cutting. I always have problems with cutting pcbs, because I don't have the tool for it. I will design a 3d modular design, but I won't print everything. I will CNC mill the frame, which will hold everything together. I have one working coffee grinder electric motor, which I will use for turning blade (probably 2" or 4" blade). Now, this motor will be fixed on a bracket. For better understanding, I will try to do something like this:

**broken link removed**.

Of course, everything will be closed in a frame, because there will be mains voltage involved.
Now, I want to make some kind of mechanism, to lift the motor with blade up and down in some limits, so cutting depth is adjustable within limits. I want it to be easy like turning a knob on the front side of a frame (I hope you can imagine).
What I am asking you, is help me with an idea, of how this could be easily and efficiently achieved. Could it be done with screw jack and in what way? I am not a mechanical engineer, so I don't have much experience with mechanics, also I don't usually get good ideas about mechanic solutions. So I am turning on you guys, to help me with my project. I will be thankful for any advice and ideas.

 

[BradtheRad]

You want a flat tabletop, so that nothing interferes with your work. (Just maybe you can have flathead screws.) Consider printing several brackets on the underside of your table.

Also bulkhead mounts (say 10 x 10 x 10 cm) which have a hole in the center which is tapped with screwthreads. The motor attaches to these mounts. Two of the mounts allow a pivoting or hinged effect. (A 3D printer is ideal for fabricating these.)

I want it to be easy like turning a knob on the front side of a frame

I guess the knob is stationary, and you simply turn it? This is possible by running a horizontal shaft from the knob to the motor. The knob pushes or pulls the shaft a few inches, therefore only a few inches at the end need to be threaded. This can be a machine screw attached to the unthreaded shaft by any convenient method.

Construct an attachment at the bottom of the motor carriage. The shaft should have no play as it moves the motor back and forth. However you cannot make a rigid mount because it needs to pivot a few degrees.

 

[bmandl]

Thank you @BradtheRad for very comprehensive answer. Please, no offence, but I do have very difficult time to picture all this. Could you, by any chance send me a simple drawing, of what exactly you have in mind?

 

[Warpspeed]

I had thought of making a PCB slicer, but I would do it in a different way.
I already have a monster drop saw with a 14" blade which is magic for cutting very large pieces of steel, timber, and large aluminium heat sinks.



A really tiny version of the same thing using a really small angle grinder would be quite easy to make with just a big hardware store gate hinge.
The advantage is you can line up the edge of the cutting wheel exactly over the cut, solidly clamp down the pcb and it will cut straight and true every time.

With a bench saw, or band saw, you need to guide the pcb past the blade, which can end up with a wobbly cut.
Even with a straight edge guide, its still not easy to get it exact first go.
I find a drop saw much easier to set up and more accurate with a much straighter cut.

 

[BradtheRad]

Simple conceptual drawing.

This does not address all problems. Some of the parts are easy to make, some not so easy. You might find an easier way to convert rotary motion (knob) to lateral motion (motor carriage).

 

[bmandl]

Ok, now I can imagine the concept. But I am all lost with mechanical engineering vocabulary, so I even don't know what to look for. What would you suggest me to start googling to get some examples? Also, I didn't meant with the knob, that it needs to be exactly like this (fixed) and rotating. I would also accept (if it would be easier to achieve) linear moving of a shaft up and down and fastening it with a wind nut or something like that on a front side of a frame.

 

[BradtheRad]

It's fine if you want to keep everything close to the motor. Of course that means you'll need to reach your hands inside the enclosure every time you want to adjust the height, etc.

Have you ever noticed a handheld circular saw is an upside-down version of a table saw in some respects? You may be able to copy its methods of adjustment. The bolt and wingnut travel in a curved slot. Or else if it's a straight slot then there is a pivot somewhere. You still have a challenge to install brackets, mounts, guides, etc. at a 90 degree angle where need be. The 3D printer is a great fabrication tool for this, wherever plastic is a suitable material to make parts from.