Indirectly Aspire

[Ms Wolffie]

I know we have a few engineers here so I am asking them for help:
I need to set the pressure on my engraving unit to 0.5 kg/approx 17oz in the Z axis.
I can only find gauges that measure in mm/inch.
Is there a formula for converting the pressure from length to weight?
If not, what is the instrument called that measures the downward pressure in weight?
I hope I am explaining it correctly.
TIA.

[Bit Breaker]

Try a postage scale. I assume you are trying to measure the downward force.

[zeeway]

Ahem...I'll give it a go. Your spec of states that the head must have a downward pressure .5 kg. Pressure is stated as force per unit of area, such as kg/ square mm, or lbs per square inch, etc. When you say "pressure of .5 kg," it is not understandable to me. Perhaps you meant "force" ?

If that is correct, as Gary said, you could use a simple weight scale to check that you indeed have that force on your head.



Hope this helps.

Angie

[FixitMike]

I would use a digital kitchen scale. Set Z0 so the bit is just touching. Then jog downwards .001" (.025 mm) at a time until the scale reads 500 grams. The Z movement required is what you want to use.

You can't really set a CNC router directly for the force. Just the amount of spring compression that achieves the force.

One could measure the spring dimensions and calculate the required compression using a spring rate formula, but that would be the hard way.

[Ms Wolffie]

Thank you for all the replies.
I wrote it is was said in the instructions. No, not Chinglish, actually translated from German.
I had a lightbulb moment last night and got the same idea.
I will put the postage scales on the CNC bed, put a square wooden block on tod and set it to Zero.
Then I can set the downwards tension on the spring to 0.5 kg.
That is the fixed point for every engraving, then the fine adjustment can be set from there and the setting repeated for another use if the same material.
There is a nosecone where every click is equal to 0.016 kg.
Cheers

[FixitMike]

As a side note, I believe that the actual setting is not that critical. What I did for my diamond drag tool was eyeball the total travel available for compressing the point all the way (I estimated that it was 1/8") and set the toolpath at one half of that. It has worked fine for me.

[martin54]

As Mike has already said it's not that critical, it is really just to ensure the spring stays under some compression at all times so if you have an uneven surface then you are not going to get low spots that aren't engraved at all.