Sizing Error!

[PhillyDee]

Help!

The time has come where I need to be half way accurate with my cuts.

Have just cut 2 items, bith are out by the same, the 250 mm size actually measures 253mm. This is the horizontal longer axis.
The vertical is 80.5 instead of 80, this is just measured with a rule for now. My large vernier is at my lasses house!

Now, how do I get it cutting accurately? The only way I can see is to alter the DPI setting on the axis in Newlydraw.

Any help iis gratefully received!!

[Daven]

I use a template with a 10mm rectangle as a reference when I draw. Then import to ND - due to the way ND imports, the drawing is combined this is handy for the next step. In ND draw a 10mm rectangle and place it over the one on your drawing - resize the drawing (hold the ctrl button to lock ratios) until the rectangles are the same size. Split the original drawing and delete both rectangles.

You can also allow for the kerf using this method so you would end up with the original drawing just larger to allow for kerf.

Hope this makes sense

Dave

[PhillyDee]

The import and newlydraw sizes are the same, so its a mchine error. I did check this using the same method

[Daven]

Could it be the belts are a bit slack? Not sure what dpi mine is set to, it's not on at them moment but can check in a while if it helps, could they have changed from factory default? Mine is cutting spot on at the moment.

Cheers
Dave

[PhillyDee]

Hmm, got a couple of clocks here, might rig them up and see if the movement is repeatable. Off to work now though!

[Spooky]

Have a look at the toothed gears on the drive spindles first Phil, they can get lose and hose your sizes quite badly.

best wishes

Dave

[PhillyDee]

Hmm,
I have had a play on the belts underneath (Its a 3020) and the left side is marginaly slacker than the other, but the largest of errors is inthe X direction. The Y has a smaller error, but is still there. It hasn't had that much useage, and I cannot see an easy way of stripping the servo's out without removing other parts. Is there a guide kicking about? I have limited tinkering time at the moment! Failing that, a quick pointer would help a lot! I am very mechanically minded, but would rather someone just told me, otherwise I would probably end up loosening something which shouldn;t be . Is there an easy way to adjust the belt tension?

Off to bed now!!

[Daven]

Hi Phill - pm me your email addy and I'll forward some info

Dave

[PhillyDee]

Cheers! Found the adjustment screws, and tightened up the x axis belt. Made no difference .

I decided to play with the SPI settings, they were at 1016 for each axis. After some minor tweaking, they are now correct at 1003 and 1004 for the x and y respectively. I will be checking every job, and if there is any slop, I will have to find out the real cause!

I just stuck in some wood, set a 200x200 square to cut at 100 mm/s and tried that 12 times or so until it came out correct. Not difficult at all, but then, I wrote the values down first .

[Daven]

Mine are both 1016! Strange

Cheers

Dave