Hi all,

First post here.

I am a woodworker, considering buying a particular panel saw which represents very good value for money, the only drawback is that the height adjustment of the saw blade is controlled by a simple rocker-type knob, rather than a hand wheel. The issue with this is that very small incremental adjustments are very hard to make on a switch/knob.

Does anyone here know if it would be practical for someone with a very basic understanding of circuitry like myself to add a fine-adjust button that can raise the blade by 0.1 of a mm per push?



https://www.scosarg.com/itech-ps400-panel-saw

Cheers

 

You would need to do some reverse-engineering on the circuit in order to "modify" it, maybe easier to design from scratch. ??

 

Likely could be done but need to know a few things:

At a minimum, need to know the DC voltage available to power the circuit.
Also nice to know but not absolutely necessary is the voltage and current the switch controls.

About how long do you think the switch needs to be closed for a 0.1mm movement?

 

Hi,

Thanks for both of your replies!

Crutschow, I think I'm going to have to go and get hands on with this machine so I can answer those questions, and try to get the schematics, which could prove difficult!

Thanks again,

Jack

 

Is the positioning mechanism capable of such precision?

You might have to add a position sensor and an MCU to move an absolute position, managing backlash and other slop in the positioning hardware. It might have to overshoot and seek to get to a position .1mm from where is it currently stopped.

If you do modify it, why not put a hand wheel operated rotary encoder if that’s the preferred control? Otherwise, a calibrated position of exactly the desired height could be entered numerically.

 

The Bearings in the Saw, and the Rail-Guide-Bearings, etc., added together,
probably have 10X that much slop,
so that much precision is probably just a dream.

The Wood being cut vibrates more than 0.1mm, even if clamped-down.
.
.
.

 

The Bearings in the Saw, and the Rail-Guide-Bearings, etc., added together,
probably have 10X that much slop,
so that much precision is probably just a dream.

The Wood being cut vibrates more than 0.1mm, even if clamped-down.
.
.
.

Hi, thanks for the comments all.

This isn't actually the case.

0.1mm is the standard of accuracy for all of my industrial woodworking machinery with digital readout and electrical control.

With a Mitotuyo caliper for verification, I work to bang-on 0.1mm accuracy every day when putting stock through the thicknesser, and when making joints/tenons on the spindle moulder (shaper to those across the pond). There are times when a piece of wood will distort enough in the planing process that it refuses to register directly to the fence of the next machine I take it to, be that a panel saw or a spindle moulder, and when that happens it is not possible to achieve the machine's potential for accuracy 0.1mm, but that potential is very much there, and achievable the vast majority of the time.

Of course, wood moves as soon as it's exposed to the elements, but that standard of accuracy is a real help when it comes to making flush joints that do not need much, if any sanding/ finishing, and ease of assembly.

 

Whoops, I didn't mean to post again! Please delete this, I don't know how!

 

it may be far better to forget the power adjustment and add a hand crank to set the height. That was my experience using a Bridgeport mill with motors. Great for traverse, useless for advancing. At least in applications where accuracy matters.

 

it may be far better to forget the power adjustment and add a hand crank to set the height. That was my experience using a Bridgeport mill with motors. Great for traverse, useless for advancing. At least in applications where accuracy matters.

I am leaning more and more this way. I can simply verify the exact height of the saw blade with a depth measuring device made for the job.

 

it may be far better to forget the power adjustment and add a hand crank to set the height. That was my experience using a Bridgeport mill with motors. Great for traverse, useless for advancing. At least in applications where accuracy matters.

Depends on the mechanics of the mill, I had a couple of knee mills I retro-fitted, including advancing the Knee, for precise positioning, ball screws are required.
It would help to know more about the present mechanics of the saw in question.
If at present, the hard positioning is due to gearing/mechanics etc ?
If so, this could also be looked at for improvement.

 

Depends on the mechanics of the mill, I had a couple of knee mills I retro-fitted, including advancing the Knee, for precise positioning, ball screws are required.
It would help to know more about the present mechanics of the saw in question.
If at present, the hard positioning is due to gearing/mechanics etc ?
If so, this could also be looked at for improvement.

Hi Max,

I believe the positioning is done by a threaded screw type design that winds the saw blade assembly up and down, sorry if I'm sure I'm butchering the terminology there.

 

Hi Max,

I believe the positioning is done by a threaded screw type design that winds the saw blade assembly up and down, sorry if I'm sure I'm butchering the terminology there.

I figured it might be !
To implement a change to the Up/Dn switch, you would have to intercept its connection to the rest of the unit and use a one-shot pulse circuit.
Another alternative would be a mechanical (gear) change, which could be more involved.
If the screw operates vertically, generally backlash is not a problem as it is taken up automatically by continuous weight.

 

I have a similar saw (Felder KF700S) which already has the type of arrangement you are looking for. A couple of observations:
- you already have the digital read out so you can visually tell if the blade has gone up 0.1mm if a suitable pulse could be supplied, so an open loop controller is OK in this case (the operator is the feedback mech)
- I'd design/build an electronic circuit that can be wired in parallel with the existing up/down toggle that provides a short pulse, you'll need to experiment to see what the signal should be. Use a scope to see what the current control is doing.