Accuracy (Expected) of Stock Kit

I have a complete stock kit here I am assembling.

I am going to move to a 12’ top beam, but I don’t have the right chain length so I’ll be building it at the original 10’ to start as I want to get cutting and learning. Assuming I don’t also change the bar height, and I otherwise was “in a vaccum” accurate with all the other positions of things, then what should someone reasonably expect for accuracy of the stock kit in stock configuration (best case scenario)?

I do realize that accuracy changes near the corners and middle of the top. So perhaps the question should be, if we call those “accuracy keep-outs” what should the accuracy be in say the 3’x7’ “middle” (or is the size smaller than that where accuracy should be extremely constant with the stock setup?). To whit, I can comfortably put roughly 6’6" x 3’6" in to my vehicle with the gate closed, so I’m especially interested in how accurate I might be other that reduced surface.

I’d like to have a baseline so I know what to expect when I pop out the other end, and that I can compare to as I implement suggested upgrades. I’d like to contribute to the body of knowledge on how different changes influence accuracy and I hope to have some time this summer to contribute and do a bit of testing and comparison.


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There are so many variables it depends on, the better you calibrate, the wider and higher you go.
Here is just a sample image

It’s not clear lines as in the picture, more a transition area where it gets worse.
In the white, with a accurately built sled and centred bit, you should be able to get under 1mm accuracy.

Kind regards, Gero


Thank you, I hadn’t managed to stumble across those particular graphics with the grid before.

It looks like the sweet spot would be in the 4’ x 7’ zone “on center”, is that a correct conclusion to reach or am I misunderstanding the scale of the drawing?


Best would be to download the py script, open it in a text editor, adjust the parameters to your setup, save the file and run it.
Again, you will only get a good guessed estimate :wink:

If you need help how to run the script, let us know.


It will create a similar picture for your setup

Thanks, I’ll give that a shot.

@Gero I see you mentioned that you didn’t cut any of your sleds on your maslow. What were they cut on? And what material did you use? Do you have a design file you can share?


Search for ‘router circle jig’ and you will find lots of easy builds.
I had a jig with my router that just had a rod with a ‘nail’ for the pre drilled centre hole.
My suggestion:
Mark an accurate angled cross on the material, drill the centre hole of the sled the same size as your ‘nail’ in the jig. Cut the circle and base all measurements for mounting the stuff on the centre and the cross.
Edit: Cut the centre hole with a circular cutter last.

Edit: My current sled was cut on an old china desktop cnc, but i had to go small and not sure if that is good.
If you have access or know someone and can afford it, let the sled be cut on a professional machine.

Ah interesting. I actually bought a jigsaw table from Germany that has a special adapter to cut circles. I’ve not used that accessory yet but this looks like it could be a nice way to try it out. You might find the whole setup interesting, you can find it here: and there is a video for the circle adapter too, below the main one.

I have no reason to believe it won’t give me a perfect circle. If so, it seems like I should be able to cut a sled, although I’ll need to check how big I can go (I do have the extension arm). Looks like I can do up to 390mm (~15.25") diameter circle with the extension. Is that large enough?


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I don’t recall the ‘standard’ sled size and far over bed time :slight_smile:
See you soon.
This might be far outdated, i did not check.

the critical thing isn’t that the sled be a perfect circle, but rather than your
triangulation kit be centered on the bit (in the stock kit, this is the ring)

several people have said tht they got a ring that was slightly out of round and
had to be forced into round by the mounting.

David Lang


Ah, I better wander out to the garage after dinner and take a closer look at my ring…

Maybe use that circle jig to make a bit centering tool.