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UniStrut Frame designs

Welcome Amubu!

That is an interesting idea for aligning the motors. I assume you mean adjustment in the z-axis? If so, most of us have found that setting the motors to the most often used stock thickness and leaving them there is fine. I have set mine for 3/4" stock and have cut 1/8 to 1 inch stock without changing the motor mounts and without any issues. If you are planning to have a very large difference in stock thickness where the median stock thickness would be more than about 1/2" from the minimum or maximum stock thicknesses, then you might want to move the motors. But I think for most of us, constantly moving the motors is unnecessary.

As for the unistrut frames, you may want to do a quick search while you wait for the folks on this thread to get back to you. I used only one piece of unistrut for my frame (the top beam), since the rigidity of the rest of the frame is less essential than that of the top beam.

This might also be of interest to you:

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Yes, I was thinking of the Z axis. Thanks for the feedback, it does make sense that with the tolerance that the chain provides that there shouldn’t be much need for moving the motors.

I look forward to building my frame here soon so I will have a bit more hands on and a lot of this will be much more clear.

Sorry, I wasn’t quick enough with my edit to get the rest in before you responded :confused:

Building your frame will definitely make a lot of things clear to you. I would start with some kind of full design idea (I didn’t bother to draw mine up completely) so that you can think about what modifications you will likely want to make early in the process. At this point there are a lot of modifications out there, but everyone’s build and needs are different, so…

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I second this, and would add that you will benefit greatly by sharing your design with the community and asking for feedback before you start… Lots of eyes here to see things that you might have missed… Wish I would have done that.

I did a strut top beam, 12 gauge, and thought surely that would be rigid enough… In reality it is really not that rigid and likes to twist. If you use strut get the thickest gauge you can get and make sure to attach supports to the top beam as close to the motors as you can and be very generous with the number of supports along the length of the strut.

A square tube will be much more rigid than the U-shaped strut.

I would also look at @c0depr1sm ‘s build (and calibration) which has resulted in the most accurate Maslow I have seen yet.

What if you replaced the uni-strud with a pipe and attached directly to the wall? You could get almost flat against the wall in the closed or storage position. You would just need to figure out how to mount the motors.

This looks to be the best thread for my 'unistrut frame design :slight_smile:

So these were my design problems to solve after reading the forum.

  1. Flex of main beam
    = Unistrut Deep Slotted Channel Heavy Gauge x 3m, (41x41x2.5)
  2. Size to accommodate larger baseboard &
    = base board made from 2 sheets of 2440x1220 which include the first sled
  3. wings to attach virtical chain
    = wings used to secure additional baseboards
  4. Minimal unistrut costs
    = 1x 41x41 3m main beam & 2 x 21x41 6m frame and support
  5. adjustment of motors parallel to working material
    = Slotted unistrut Cantilever Arm
  6. ease of dismantling and storage
    = bolt together unistrut brackets
  7. no screws in base board to damage router bit
    = central baseboard held inplace by dowels into unistrut, wider base board bolted to unitrut wings
  8. ability to hold working material
    = larger base board to allow for holes for camlocks


image shows the baseboard cuts to make the over skits and sled

open questions:
do I need 10’ main beam or 12’?
will there be twist in the motor mount supplied in the kit? and should the main beam be a 40x40mm box section with motor mounted interally

parts required , plus bolts

What are your thoughts. thanks

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For the attempt to use an entire ply-sheet you will have more joy with 12ft.

@Gero Thanks.
So this picture shows the difference to the chain angle at the lower edge of the working material.
21 deg verses 13 deg which would be the same angle as working 30cm in from the edge

Do I need a longer chain than come in the kit to achieve this?

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Yes, do not trust my numbers (don’t worry, this amazing people will correct me) as i can’t look them up right now, but depending on 12ft motor distance:

  • 12 instead of 11 foot chain, or slightly more
  • the height of your motors over the sheet also counts

Try the approach how much chain do you need if the sled (the bit) is in 1 bottom corner.

Yes, do not trust my numbers (don’t worry, this amazing people will correct me) as i can’t look them up right now, but depending on 12ft motor distance:

  • 12 instead of 11 foot chain, or slightly more

slightly more, go for 13 ft to give you lots of room. You want to be able to
have the chain reach from motor to motor

  • the height of your motors over the sheet also counts

very much so, look at the spreadsheet for exactly how the different options end
up.

David Lang

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Very nice design! It’s obvious you put a lot of thought into this; that is awesome. I used a 12 gauge strut for my top bar and found that it flexed and twisted way more than I thought possible. My advice is to anchor more supports to the top bar, especially at the ends where the motors are mounted.
Edit: Also I noticed that you are planning to use smaller sections of strut to construct the total length of the top beam? I’m wondering if that will have an effect on twisting or even level orientation of motors relative to each other?

I would also add one more support in the middle of the work space to prevent the spoil board from sagging which will cause some issues later.

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Thanks for the feedback.
As my design was all conceptual I appreciate your advice.
For the difference in price for the 21x41 unistrut to the 41x41 (12 gauge), I was going to use the larger deep strut on all parts.

Arh, good spot on the detail of the picture, the top beam will be a single length, I was lazy in Sketchup as only had a 500mm strut example and stuck them together

Also a good call on the length of overhang to the motors, originally with a 10’ beam I only had 500mm to the motors but with a 12’ beam it will be much more. Inaddition I wasn’t sure how much the spoil board would flex as it was framed , so I’ll add another central upright which will allow me to space the outer uprights closer to the beam ends and motors.

I’ve not put my order in yet, so more thinking to be done.

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@wrightwells Yes this is a very fun part of the process! I wish I would have submitted my design/thoughts before building as I’m now taking apart my frame to shore up some weak points. Keep up the good work!

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@wrightwells Would you be able to share your SketchUp model? I’m about to build my frame as well and torn between wood and unistrut. Much better equipped today to do it in wood but if there is no welding required in unistrut it is very intriguing…

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@JWoody18 yes Jeff no problem, how do you want it?

A Dropbox or Google drive link works. Any chance you can save it in 2016 format? Thanks

Jeff

if you wanted to mount motors to cheap galvanized conduit tube, you can just take a short 2x4 or 4x4 and hole saw drill and stick the tube in the wood and secure with some drywall screws to prevent rotation. see photo sample of one end.

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here is the spreadsheet, it lets you see the angle and force differences with different setups

you may also want to look at these motor mounts I designed New motor mount suggestion

for mounting the top beam and having it be adjustable, look at this post using a unistrut angle and short piece of unistrut to allow the top beam to be moved in and out easily

(lots of useful info in that thousand post thread)