Calc for effector arm lenght.

tecno

As I am about to make new magnet arms to my Dreammaker Overlord Pro now with Smart effector and steel balls.

Does anyone here have a DOP rebuilt with Smart effector that can share dimensions used?

tecno

Rephrasing my question, any calculator to use for this that is clearer than mud ?

tecno

As you can see the DOP effector is way much larger than Duet Smart Effector.

tecno

Here a solution that I think will work OK

http://danalspub.com/DKcalc/?he=305&ve=620&dr=226&lr=440

droftarts

@tecno What is your current M665 setting? Are you changing to a Smart Effector and Magballs, and changing the carriages as well? All these will change the Delta Radius. See this image for what you are trying to measure:
alt text
Realistically, you can roughly measure the carriage and effector offsets, and let delta autocalibration dial it in accurately.

However, if you're trying to determine the length your rods should be, that's trickier. Ideally, you want the angle of the rod to be, at minimum, 20° when the nozzle is at full extent away from the tower. Any less than this, and the speed the carriage has to go is over 3x the horizontal speed of the nozzle. This page explains this.

Of course, long arms mean a reduction in build height. So it is always a compromise.

Probably the best thing to do is mount the new carriages, and with them at the same height measure between the centre of the X carriage Magballs to the centre of the Y carriage Magballs. Then measure between Y and Z, and Z and X too. Hopefully these three numbers are roughly the same. The radius from the centre to the carriage will be:
Circumradius of an equilateral triangle of side a is a / sqrt(3)
This gives you the Delta Radius + Effector offset. With a Smart effector, the effector radius/offset is about 22.8mm, so take this away to get the Delta Radius.

You can then make some decisions about how long the arms should be. There's a couple of delta calculators around that should help you decide on this. Just remember you are measuring from joint centre to joint centre. Alternatively, contact Haydn at https://www.magballarms.com/ and I'm sure he can advise/sell you a set.

Edit: just saw this on Haydn's site:

A handy rule of thumb is that the arms need to be about 120% of the bed’s diameter, so a 300mm diameter bed needs 360mm length arms to easily reach the edges.

Hope that helps!

Ian

tecno

@droftarts

Hi Ian,
This whole Delta thing is muddy for sure. If I go with Haydn's 120% I loose ~40mm in build height.

Re the old effector that is larger but also nozzle only protrudes about 2mm under the effector so it is not so easy to get the print volume close to original. So I think my calc linked above will have to do.

Old build volume

droftarts

@tecno You may lose a bit of height, but with a smaller effector you can print bigger in X and Y. So the arms may need to be longer if you increase the bed diameter. If that is fixed, then probably not important.

Ian

tecno

@droftarts

Opting for Ø200 so it is like the spool in picture