I see your point. However my experience with captured nuts is that they do not slide easily. Once tightened the teeth cut into the beam, and by design they lock into place when installed. The idea is to allow smooth movement of the top beam on the horizontal rail sections. That is why Iāve used the carriage bolt & washer arrangement.
The 2 short bolts holding the horizontal rails make them absolutely rigid tied to the upright support unistruts. The intention is to remove even the slightest flex in the position of the top beam as the stresses of the sled pull it at multiple angles. The rest of the frame structure will stabilize the upright support unistruts as well.
Chain interference with the horizontal rails will not be an issue considering the 12ā top beam will be 2ā out and 2ā up from the 4āx 8ā work area.
Another issue: Using wood for the structure is relatively inexpensive but by its nature swells and shrinks with changes in humidity. This may not be a problem for many users however for me maintaining accuracy is extremely important. I intend to use wood for media support but in ways that allow for its instability.
remember, the chain angle at the top is only 10 degrees from horizontal. this is a drop of just over 2 inches per foot, so at 2 feet, and the need to drop 2 x 1 5/8 + distance from top beam to the top of the chain, you are actually going to be getting pretty close (and if you used a 10ā beam so that you only had 1ā or so to the leg, you would be in trouble)
remember, you arenāt expected to adjust the beam position very frequently, only when you are changing your workpiece+wasteboard thickness significantly. you have a 1" or so variation in thickness that you can use in any one setting.
Thanks for your input. Yes, you are right that for most people the chain spacing will not be much of an issue and I admit for most my design is probably overkill. Personally I need a great deal of flexibility for working with non-standard media - thatās what Iām planning for anyway. Iāll post photos and info for ideas and suggestions as the frame comes together. Thanks again - I appreciate your help.
Less than 90 minutes with Documenting - I will say it will be under 60 minutes. Screw count 9 - This is a minimum build but I believe it will work. Itās designed to mount the work to the frame and have it flush with the outer edges for full access to the entire sheet.
2- 12 ft boards
1 - 10 ft board
1 - 8 ft board
1 sheet of wood . 3/4 inch thick
Note there are 2 side pieces and 12 screws not in place.
The top mount is deviated from the drawing slightly. The total build height 6 foot 8 inches. The full depth for stroage when folded 12 inches deep.
Assembly instructions for the Maslow frame. This process deliberately avoids specifying measurements. Instead everything is positions by using other boards that have been cut as spacers. This produces more consistent results
The only measurement thatās needed is when you are squaring the frame, and that can be done with a piece of string (just use something that doesnāt stretch)
To keep everything square, you want to have a factory end on the 72" front legs, one of the 60" back legs, the 10" top beam supports, and two of the 24" pieces for the rear kickers (Iāll post a revised cut-list to show this grouping,probably graphically)
When fastening with glue and screws, the main purpose of the screws is to hold everything together while the glue dries, but they also provide a backup if the glue fails. āreal woodworkersā can flatten/sand the surfaces and glue and clamp instead of screwing and end up with a good, strong joint. Normal people should leave screws in place ļæ¼
This is ordered to keep things as small as possible as long as possible so that most of the work can be done on a bench/table
Options
There are a few common variations on this frame
additional wasteboard support
Some people live in areas where the temperature/humidity can change rapidly, this can warp the plywood. Other people are experimenting with using sheets of foam for the wasteboard. By adding a couple extra boards to the Maslow, the main plywood board is not needed and the wasteboard can be mounted directly to the frame
Support for cutting extra thick/thin material
By default, the Maslow can cut material up to about 1" thick, this variation allows for more thickness
unistrut top beam
Unistrut is a metal beam commonly used to support pipes and conduit in industrial buildings. (in the US, Home Depot and Lowes carry it, but not always in stock). It is a 1 5/8 (41mm) channel that is designed to hang things from easily. It is available with holes already in it and will be a little stiffer than stick lumber and will not distort with humidity changes.
Assembly Instructions
attach kickers to front legs
use spacer blocks under the combined legs to lift them 1.5" off the ground
take a 60" rear leg and clamp it to the side of a front leg with factory ends together and flush.
put a spacer block narrow side against the bottom of the 60" piece
position the kicker against the ground and the spacer block (on what will be the outside of the front leg, so one on the left and the other on the right).
Check that it is square
Fasten to front leg (screw and glue)
IMPORTANT: This is one of two places in the build where the angles and distancesare critical. Make sure that the kickers are as square to the front legs as you can make them. Use the same pieces of wood as spacers for attaching the kicker to each of the front legs.
attach the leg spacer to the rear kickers
place a block along the inside of the rear kickers (on the same side as the leg), flush with the back of the kicker
glue and screw the block to the front leg.
position the top cross-member block not used on minimal version
take the two 16" diagonals and set them against the lower block
position a block flat against the leg, with the grain forward
glue and screw the block to the front leg.
IMPORTANT: make sure the block does not slip and extend forward of the front leg, with the kicker sticking forward of the leg it will not sit flat on the ground
attach the rear legs to the front legs
lay the rear legs next to the front legs with the bottoms flush
drill through the back leg and use a lag bolt to attach it to the front leg
angle the rear legs
pivot the rear legs so that the edge of the leg and the top corner of the rear kicker line up
glue and screw in place)
connect the front legs with cross-members
attach one 82" cross-member across the top of the each of the set of blocks attached to the front legs, glue and glue and screw into the block
The bottom of the cross-member will be even with the top of the kicker
*IMPORTANT: make sure the cross-members doe not slip and extend forward of the front leg, with the kicker sticking forward of the leg the front leg is up off the ground
Optional, not compatible with minimal frame connect the verticals to the cross-members
use the 28" diagonal brace pieces as spacers to position the verticals in from the blocks (exact position is not critical)
glue and screw
NOTE: this is fastening into the end grain of the verticals, which is very weak, but these do not have much force against them (they just support the workpiece/waste-board) so we can get away with this.
Optionally cut 4 more blocks and use them in the corners.
square the frame OPTION cut the corners off of the crossmembers so that they do not stick out beyond the boards they attach to
If you are using both crossmembers:
use a string or tape measure (requires an assistant), check that the diagonal distances between the corners of the cross-members are the same. If they are not, rack the frame until they match (push on the corners with the longest distance to distort the shape)
glue/screw the 16" diagonal braces across the back of the frame, attaching the legs to the lower crossmember
glue/screw the 28" diagonal braces across the back of the frame, attaching the legs to the upper crossmember
If you only have one crossmember
use a square to align the legs square to the crossmember
glue/screw the 16" diagonals across the back of the frame, attaching the legs to the crossmember
Optional connect the rear leg crossmember
connect the 88" rear crossmember to the rear legs so that the ends of the crossmember are flush to the outside of the legs and the crossmember is resting against the kickers
prepare the top beam
if using the unistrut mounting (depth adjustment option)
place the 6" unistrut pieces on top of the front legs, flush with the top of the leg
place the top beam centered across the unistrut pieces, flush with the top of the leg
mark the sides of the unistrut on the bottom of the top beam
flip the top beam and attach the unistrut to the top beam at the marks, with the end of the unistrut flush with the front of the beam.
place the spring nuts inside the unistrut
attach the metal angles to the unistrut
if using wood supports for the top beam
clamp the 10" top beam supports with the non-factory end flush to the top of the legs on the outside of the front legs
center the top beam over the end of the top beam supports
drill through the top beam for bolts to the supports
drill pilot holes in the supports if you are using lag bolts
remove the top beam and unclamp the top beam supports
stand up the frame
attach the top beam
if using unistrut
position the top beam and unistrut assembly on the top of the legs
drive lag screws through the angle into the legs to anchor the beam in place
if using wood supports
square up the 10" top beam arms against the top of the legs.
glue and screw in place
attach the top beam flush with the front of the top beam arms.
IMPORTANT: This is the second place in the build where the angles and distances are critical. Make sure that the arms are as square to the front legs as you can make them, and that the edges (top AND back) are flush.
@bar, please install the top blocks, but then build the minimal frame up through standing everything up (without gluing the diagonal braces)
then go back and remove the diagonal braces and go back to step 6 and add the upper crossmember (donāt bother with the verticalsor the rear crossmember), and proceed adding all the cross members, again though standing everything up.
I think the added rigidity is worth the extra piece of lumber, but if you really think itās not, and itās a lot of extra work, we can make it the āextra stiffā option. even with the two diagonals, I think itās going to be wobbly when trying to set up the top beam
a good place to get bolts (US and metric) is https://www.boltdepot.com they ship things out the next day and use US priority mail (typically 3 day delivery) which allows up to 70 pounds/package, so shipping is pretty cheap.
the bracket used for the adjustable ones are $4-6 each in quantity (search for p2484 on google to find a bunch of links). This is the same one shown in the unistrut build yesterday, the unistrut is $3/6" piece from home depot, so Iām sure you can find it cheaper elsewhere (at home depot itās under plumbing accessories, pipe hangers)
Is Figure 14 the correct drawing? It appears to show unistrut arms with a vertical wooden top beam and not wooden arms with a horizontal top beam.
Also, if having the top beam horizontal is not a good idea and the only reason we are doing so is to avoid the solution of drilling all the way through the edge of a 2x4, arenāt there other solutions that would work well enough? Thereās not a lot of forces acting on this jointā¦ basically, it takes a small share of the weight of the beam, sled, motors, chain, etc. because the arm is tilted at 15-degrees. The only thing it really needs to do is to keep the top beam from sliding off the arm. Why not just put in another block of wood like we do with the other members.
Edit: if you do the change to the cutlist detailed in next post, you have enough room on 2x4x10 #7 to create two 5.5-inch blocks. All it takes is one additional cut since you will be left with an 11-inch piece of wood. Those two blocks and some screws and Bobās your uncle.
Which one is optional? The top? Need to indicate which one in the instructions. Also, if one of the crossmembers is optional, then a set of the blocks should also be optional, correct? If so, should move a set from 2x4x10 #7 on the cut list up to #3 on the cutlist (if you follow).
Iām going to hold off on this until @bar builds the frame and see if we really need to have the version without the top crossmember. Iām hoping that the result is just floppy enough to be worth using the extra board and not have to list it as an option
For me, itās more that if itās only anchored at the back, there may end up being a gap at the front. in your first drawing a few posts ago, thereās nothing pulling the top beam down against the support, itās all strictly being pulled against the block in the back, and a gap can open in the front. If you were to make this joint with gorilla glue, the expansion of the glue would tend to tilt the top beam.
pulling down against the support doesnāt have this problem, the clamping force of the fasteners pulls the two factory surfaces against each other.
In your post with the images embedded into the instructions, the last image is Figure 14 but should be Figure 13, I believe. You have Figure 14 twice in that post.