[bb237]

Hello! I'm a newbie here,

I am trying to make a gantry structure for a 3D printer. I plan to use a T-slot frame for the gantry structure. However, I have a few questions regarding the structure:

1. Perpendicularity and alignment of the structure. How do I ensure it is configured correctly? Are there any online resources that I can follow?
2. I will be using two linear motors for the X and Y axes respectively. I am not sure how to maintain alignment since, for one of the axes, I am using a linear motor with two guide rails. I am afraid I may loose alignment when using it for printing. I have attached a picture of my design for more clear understanding.

Details about the structure:

T-slot frame with a base of 4ft x 4ft.
Linear motors: Aerotech Pro115SLE (200mm travel distance)

Feel free to provide any advice or resources that could help. Also, let me know of any concerns that you have regarding my design. Or if you any more infromation
Thank you!

[peteeng]

Hello BB - The technically correct way to align such a machine is to use a geometric laser metrology set up. Unfortunately they cost well over $25000USD to buy one. Maybe you can hire one nearby you?

Small CNC Machining Centers, Multiturn/Millturns and Lathes - HamarLaser

At Hobby level its trial and error. Mark out a square that is large on your table (say 150x150mm) and make that square via cam. Then measure across the corners and establish if its square and accurate. Then mechanically adjust the machine until it can make that square correctly.

The two rail idea is good but in practice its not necessary. A correctly preloaded (use med or high preloaded bearings, do not use ebay bearings as they will have clearance and give you grief in motion and accuracy) and sized single rail will be easier to set up and run fine in your application. Running linear motors on construction extrusions seems to be an interesting mix. Your frame will need cross bracing, linear motors have very high speed and acceleration capabilities and that frame will need to be held together on something solid otherwise it will dance around when it moves. The linear motors are far more advanced than your structure. You could achieve the same using good quality ballscrews and servo motors even steppers at a far lower price unless you have been given the drives?. What speeds, accuracy & accels do you want to achieve? Good luck - Peter

[bb237]

Hello Peter,

Thank you for you for your reply. I am using the ball bearing from McMaster Carr. I guess they should be good enough for the use. I will look into cross-bracing and will add it. Also, the speed I am looking at is around 20-40mm/s with an acceleration of 3000mm/s2. I know these are pretty high speed but the linear motor is capable of this. My problem currently is the load due to the structure and speed I am trying to achieve.

It would have been easier if I was using a moving bed configuration but I am using an AM process which uses a powder bed for printing. So, its not possible.

Also, do you know of any similar designs/resources that I can look at and follow or take inspiration from?

[bb237]

Also, for alignment, I bought a set square and dial gauge. I guess I can use that too for alignment. Its quiet similar to your approach.