Print directly on build tray


#1

Hello,

I have designed a omni-wheel and would like to 3D print the body of the wheel as well as the little rollers on the side (somewhat like this picture: https://gtfrobots.com/wp-content/uploads/2016/10/SW-704-B.jpg).

1: I wanted to print the little rollers (which are 4mm tall) directly on the build platform because I want to save resin. The only issue is that they need to be perfectly strait so do you think that they will bend when curing? And if they will is there any way to get around them bending?

2: I also was wondering which resin to use. These wheels are going to be lifting up a 2400 gram robot (4 wheels) so each wheel will have 600 grams of weight on it. I was thinking either tough or durable resin (Form 2). Which do you think would be the most desirable for me?

Thanks,

-Bend It Like Beck Ohm


#2

Printing directly on the platform will result in compression of the first layers (first millimetre or so? I assume this depends on print layer thickness), ie. it won’t be accurate to your STL. Sounds like this wouldn’t be acceptable in your case.

You could perhaps take down the base thickness and height above the base to save a few layers and a few cents.


#3

Hi Kristian,

Thanks so much for your response. I agree it is a bit risky so I think I am going to do what you recommended. But I am still confused at which resin to use.

Thank you


#4

I found this number on another forum post but it worked for me. Just add 0.022" (inch) to the surface that will be touching the base.

Here is the model and you can see where I “pulled’ some of the surface up 0.022” so the rounded edges will print as expected. I forgot to include the outside edges and you can see in the next image where those we slightly compressed compared to the inner rounds. It was printed upside down and directly on the base plate with no supports and turned out great.

Here is the final output from Form 2 with Std Grey at the lowest resolution.

This adapter is holding a magnifying lamp arm onto a tool cart I was customizing. It works really well with a few wood screws.


Compensate real z offset in Preform
#5

I find it very interesting.

But I can not make that impression with my form1 +.

In my case however much I print on my base of form1 + I always have a wrinkled layers.

How do you get that perfect result without wrinkled coats?


#6

You will have to measure your compression. After that, you will need to measure the extra thickness added as part of the raft routine added. Then you will have to subtract that from your model.

Or just follow FL’s suggestion and print with a raft and supports. Then just post process your model to remove the support bumps.

Another option would be for you to create a custom ini profile to be used in OpenFL. It will take time to fine tune but you would then be able to minimize the over exposure designed in for raft adhesion and raft strength.


#7

The degree to which a part warps is largely a function of the ratio between the length and thickness of the part and I don’t think that you’ll run into any issue printing the rollers directly on platform.

Both Durable and Tough Resins should work well for this. Durable has a bit more give and a higher flexural modulus than Tough Resin which might not be optimal based on how the wheels are being used.


#8

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