Belt Tension Tip on SO3


(Dustin S Tilton) #1

I noticed my pockets were running a little short in the X axis, so today I decided to re-tensioned the X and Y belts, as I could get a finger under them pretty easily. i was having a hard time getting them tight. Then it dawned on me to try a longer screw. So I grabbed a long screw and now my belts are finally tight. I started calculating for belt stretch to make adjustments, but after cutting several circles and square pockets of various sizes I was already within .002" using the the default 40mm per step setting. So I decided that is close enough for what I use the machine for. Next I measured a piece of MDF using calipers, and it was .26". So I set up a test to cut a .26: deep pocket. I think my Z is off by a couple thousandths as well, as I could just feel the edge of my MDF gauge with my fingernail when I put it in te pocket. I have a new Z belt, but I finally have the Dewault trammed and pockets are cutting beautifully, so I decided to leave it for a while while I decide whether or not to convert to a linear Z slider from CMC4NEWBIESon eBay.

Oh yeah, before cutting anything I jogged the machine over to each end to make sure the longer tension screws will not interfere with anything, and it is all good.


(Jonathan K) #2

tell me more about this.


(Dustin S Tilton) #3

The linear slider from CNC4NEWBIES is being used by quite a few over on the Inventables forum, and so far I haven’t seen a bad review. Just go over their and search it, there are several threads. It looks like the latest offering offers 6-7" of Z travel (some people are lifting the gantry via the X plates or via the Y plates) and they are now offering a fast pitch screw. The company is pre-drilling for the X-Carves, so it is a simple installation. I have a picture of the Shapeoko 3 X axis plate with dimensions, but not the actua dimensional drawing PDF file. So I need to send them specs for the holes I need drilled to match holes already on the plate. I emailed them about providing a pre-drilled version for Shapeoko 3 users, but have not heard back. I need to try to contact them again.


(William Adams) #4

FWIW, as I’ve noted previously it ought not be too hard to convert an SO3 over to an Acme Screw drive: https://www.shapeoko.com/wiki/index.php/User:Willadams#Acme_screw


(Luke) #5

How would you go about calibrating the machine to accept the different movement?


(William Adams) #6

Calculate the number of steps per https://www.shapeoko.com/wiki/index.php/Grbl_Configuration#For_Z: and update $102.


(Luke) #7

Incredibly interesting. I have never played with the GBRL setting since getting my steppers. I found a dead link on the calc to work out the micro steps per MM.

I also found this site:

very interesting - I’m going to have to play…


(William Adams) #8

Note that there’s an article on this here as well: http://docs.carbide3d.com/shapeoko-faq/how-to-calibrate-the-machine-for-belt-stretch/


(mikep) #9

I asked them about this… There is a $34 adapter plate for the “LP” model. With that, it’s supposed to bolt right up.


(Dustin S Tilton) #10

How did you contact them? I filled out the contact us form on their website and have not heard back, but I see lots of posts where people say they messaged back and forth with them. So I must be doing it wrong. Thanks


(mikep) #11

Just using their contact us form - took a couple days before i got an answer, but they did answer.


(Dustin S Tilton) #12

Thanks. I got ahold of Joe. Ordered my Z Slider today. It comes with an adapter plate drilled to fit on the Shapeoko and he is drilling holes so I can use the spindle mount. It should arrive early next week. I hope to get it installed soon after. I will post pics and a review.


(Dustin S Tilton) #13

@UnionNine see my install log and review here -