[curiosity22]

G'day folks,

Well big rookie mistake on my part. As some of you may recall I was having issues cutting perspex and attaining a reasonable speed with my cnc. Thinking it was UCCNC tried lowering accuracy etc etc..

I put that aside thinking the answer will fall over me eventually and it did today using Jointcam.

I thought I would try my hand at making a blind dovetail, machine movement was ok till i tried cutting the dovetail and my cnc was literally moving at snails pace. I switched over from UCCNC to Mach... same issue.

Checked the Gcode looked ok etc etc, half an hour or so later I checked the feed.

Voila, my rookie mistake uncovered!!

I incorrectly assumed when I switch from inches to mm that all measurements and other stuff is also recalculated.

WRONG my dear lord so wrong.... I only noticed this because the tool and relevant data is on the same page!!

One of the feeds was 70 inches per minute for one of the dovetail bits, well switching to mm that number of course didn't change..!!! When the penny dropped I googled 70 inches what is it in mm entered that number and my machine came to life.

So when doing the trial blind dovetail, my machine was moving as it was meant to at 70mm per minute, just a little bit slower than 70 inches per min.

I checked some other software I was using and of course YUP same thing, the measurements, rulers etc switch from inch to mm but not the feeds or anything else related to the tools!!

I grew up with inches yards chains and furlongs, and even today a mm means less to me than what fractions of inches do so it never tweaked that I had to change the later.

So switching from inch to mm all except .... is updated.....

Its something I would rather have kept to myself but there may be some other poor bugger out there who is maybe making the same mistake.

Don't laugh to loud folks...

Wasn't the machine, wasn't the software it was a Rookie mistake one I hope not to repeat.

Has anyone else made this error or can I claim to be the first

A small suggestion to Coders, you don't have to add lots more math to your software, but maybe a popup warning when switching from inch to mm or visa versa /// a simple Hello don't forget to check your feeds they are not modified you need to change them manually.

Cheers and greeting from the Colonies Downunder.. and G'day to you all..

Steve...
I can stop chasing my tail now.

[ger21]

Not sure exactly how you are switching from mm's to inches, but JointCAM has a couple options for unit conversion.

[curiosity22]

Ger,

In config, my first mistake was I assumed the inch (g20) and mm (g21) was it.

Then I saw the unit conversion inch to mm then convert feedrate.

That opened my eyes to why I wasn't going so well with my other project.

Other software not converting feedrates.

So Jointcam fits all the bills for conversion, I didn't see it at first but not all other programs do the same.

Going back into my workshop to readdress some stuff I was trying out couple weeks ago.


Cheers,
Steve

[Sterob]

"If your not making mistakes, your not doing anything....."


lol

[curiosity22]

I try to tell my wife something similar but I can't read grunt or head bobs lol..

Cheers mate

[ger21]

UCCNC is unitless, so G20 and G21 will have no effect.
In JointCAM, are you designing in inches, and exporting in mm?

That's what the unit conversion is for.
If you just need to convert the feedrate, you can use the feedrate scaling option.