Thread: Chris's First CNC Build

Looks fairly good now

How big is a 50mm square and a 50mm circle? Bigger or smaller or exactly the correct size?

Then you will know if you have things set correctly

You will know when you are missing steps....

Hello Blueray

Nice star!!! 8-).

Glad you have got it working, good feeling???

As far as speeds go, you won't have enough power in the router to cut and move without stalling the router or tearing your work, unless you have really shallow cuts, as others have said, what sounds right ( for the router ) generally is.

For rapids yes speed is good but if you lose steps in a rapid move what good will that do if the rapid is between cuts, is it a problem if it takes 45 seconds to go from one end of your table instead of 30?? still quicker overall than you can do by hand.

Onto the Z now???

Ed

Any signs of missed steps then reduce the acceleration/velocity. You will find it will just make wierd noises and lock up when you have exceeeded the max of the motor.

You can do a repeatabilty test where you get it to travel on all axes a certain distance then return it to zero. Do this say 20 times and then check if you axes are at the starting point.

Set you machine with Z axis on the table and mark the point where it is resting. Set all your DRO's to zero.
A simple file would be

G0X200Y200Z100
G0X0Y0Z0
Note it is G Zero.
The Z direction is upwards so it is not going to dive into your table unless it starts missing steps.
Either keep running this as a single block of code or copy this block another nineteen (or whatever) times done the page and run it.
If at the end of it your machine is still in the same zero location you are OK.


Geeze you have to be quick typing on this thread - by the time I reply there are heaps of posts in between. )
I recommend you get all axes working before you go too far. Z not being powered will have little resistance and could unwind during a cut.

Hello Blueray

FYI looking at the star resting on two points, the length from the " top " to either of the two points should be 95.1057mm, if you have used the outside of the line file it should be close to that.

Ed

Hi Ed,
You have to laugh at us. In a woodwork forum and we are quoting 4 decimal places
It's all relative to us but must seem a bit strange to non cnc'ers on this forum. We are a wierd lot with verniers instead of folding rule in our pocket.

yea its a good feeling to get it going.

I had the X axis flying before but had my finger on the stop button and as soon as it whined I stopped it. Almost made it to 2000 mm/min, of course it could never cut at these speeds (maby shallow cuts)

Shouldnt be long now till its complete, limit switches go on tommorow (I loose 3cm on the Y axis as I can only put them in one spot

Hello Rod

I just assumed that everyone can measure to four dec' places ( I can't either ) don't worry though, I found out the hard way that even pressing a bearing into a 6 thou undersize hole isn't good, I had to buy a mic as the calipers just wouldn't go to 4 places.

Anyway, glad you got a laugh.

Ed

Installed the limit switches. Now gota work out the wiring.

Worked out my table length also now.

Because of the bad design. I have a table of 1280x760 and a min cutting area of 900x520.


But its big enough for my next machine which I want to build from it, I would have loved a 1 metre X axis but its only the first.


No pics as my dad took off with the camera I wont have any more pics till the weekend.

Hi Chirs,
Unless you build a 2400 by 1200 travel machine they are always too small for all jobs. You have a good size cutting envelope so I would not be worried.
Yes we need some pictures.

Just playing with the cnc router I am starting on a prototype of MDF for a long axis machine (2500,1400) to cut a full sheet 2400,1200

I am having problems getting a accurate setting for the motor movement.


Just cut a 240 x 100 design, it is about .5mm short on the top and 1 mm on the width.


Whats a accurate way to measure it? (steps per unit)

Hi Chris,
Assuming you are using Mach3 try this.
Go to Settings
Above the Rest button is Axis Calibration / Set steps per Unit
Select the axis
Type in your distance etc, etc In other words just follow the prompts. It will reset your steps for that axis based on your results.
In the crudest form use a ruler to measure the distance and if you want better accuracy use a vernier gauge. Let the machine push the jaws along if you use a vernier.
Hope that helps.

Originally Posted by rodm

Hi Chris,
Assuming you are using Mach3 try this.
Go to Settings
Above the Rest button is Axis Calibration / Set steps per Unit
Select the axis
Type in your distance etc, etc In other words just follow the prompts. It will reset your steps for that axis based on your results.
In the crudest form use a ruler to measure the distance and if you want better accuracy use a vernier gauge. Let the machine push the jaws along if you use a vernier.
Hope that helps.

Yea thats what ive been doing, ill try it again with the digital caliper as a push and not a pull.

Hi Chris,
Ok if you have been there then is it possible you are missing steps?

Originally Posted by rodm

Hi Chris,
Ok if you have been there then is it possible you are missing steps?

The latest one wasnt cut any faster than 250mm/min so I dont think that is the case.

I'll measure it up tommorow if I can get some time to do so.

Thing is also, the 8mm holes are alightly bigger for the bolt (might be the bolt) but then the design is a touch smaller.