Introduction: One Arm Printing Unit
This project is a compilation of my research around a big size silkscreening table. Focusing on the "arm" system, not on the clamping of the screen.
The goal is to be most size/quality/money efficient, a lot of material was found locally and drove new direction in the design process.
I based a lot of this project on the work of other peoples found online. The footprint of this particular construction is ruffly 2 meters wide to 1.2 m deep. It should provide a approximate printing size of 1.60m x 1.10m.
I invite you to get inspired by the ideas and add yours.
The cost of the project may vary for me it was around 35€ of material from a local supplier :
-Plywood less than 1m²
-main overkill metal tube 42mm
-aluminium square profile
-hard plastic (polypropylene but you can use good hardwood or plywood)
and 60€ of hardware :
-1 m iron square bar
- 1 M8 threaded rod
- 2xM8 and 3xM10 bolt and nut
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Step 1: The Linear Roller
The project started with this big 2 meter metal tube, diameter 42mm.
I had to work around it : its solid, strong, and was cheap
There was no pre made linear rollers of this size available online. I did mine based on what i could see by typing "diy linear roller".
It consist of 4 10mm square metal rods, 20cm long (a bit too long). Maintained by 8 x M8 metal rod and lock nuts.
I used 8 common size ball bearing and 10mm aluminium tube to center them on the main tube. An upgrade to this could be CNBTR 5243 v shaped bearing that can self center.
I adjusted the friction by simply tightening to let all the bearing get slightly in contact with the tube. Not too tight, otherwise it's not a smooth ride.
It's a good thing to already drill before assembly : for the 2 bolt who will connect the plate and arm over the roller.
Step 2: Plate and Arm
I used a piece of scrap plywood, very dense and strong to create a good support that help to ensure the transfer of mass with the aluminium square tubing.
I had to drill space into the wood for the bolt and bearing that extend a bit outside of the square metal linear roller.
A bad thing is that as soon as you bolt the plate and arm on top you lose some access to adjust the tension of the carriage. So adjust before, even if the plate and arm are just retained by 2 butterfly nut.
Having some hole to access them from the top would be a good thing. I made an aesthetic choice and did not drill through.
I added a round wood rod that fit tight inside the aluminium arm to give reinforcement and a nice handle.
Step 3: Slider on the Arm
I created in plywood an U shaped form that serves as a sliding carriage and main axis of the squeegee support system.
I drilled first the wood U and used it to drill the aluminium arm. Sliding a blot for every hole to ensure a good spacing.
10 cm spacing on the U shape wood, and 5 cm spacing between each hole on the arm to provide more adjustment.
Step 4: Squeegee Holder
The squeegee holder (the green part) is composed of 2 plates of very hard plastic (polypropylene probably), you can use hardwood or plywood with no problem i think.
I drilled the center axis and inserted 2 bearings : they act like a spacer that let the piece move freely, and will let the squeeggee lay flat on the screen even if the arm is tilted down or up a slightly.
Then, with a circular saw i cut 2 slot for the 2 tiny clamps destined to hold the squeegee. I angled the bottom of the slot with a rotary tool to provide more angular movement.
I drilled in the side of the metal clamp and screw them in place : but able to move freely since they will define the angle of the squeegee during the print.
It is important to place them so that when they clamp the squeegee, the squeegee is centered. Otherwise the short clamp can not hold or the squeegee can bump into the U shape slider assembly.
Then to be able to adjust the maximum tilt of the clamp i added from the top, 2 screw over each clamp that act as end stops. I added latter tiny blot at the extremity of the screws, hold in place with thread locker. This way the loose clamp do not jam or slide to the side of the screws (the slot was maybe too large).
There is definitely an improvement to be made on the clamping system, maybe by making it accept the shorter square squeegee generally used for this kind of printing table.
Step 5: Money Shot
There is space for improvement, mainly on the squeegee clamping mechanism.
Here is a link to the 3d model, the measurement are mostly accurate : https://a360.co/2Itnw88
I was inspired by this other post on instructable that use other solution to the same problem : https://www.instructables.com/id/One-Arm-BanditSqu...
Also the visual design is mostly borrowed from the beautiful and astonishing table created by François Chambard : http://www.umproject.com/projects#/the-print-shop
The next step is to make counterbalanced frame to hold the screen in place and a micro registration table
I wish you the best making !
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