If you want an excellent heat bed, don't bother with the PCB type - get one of these: https://www.printitindustries.com/produ … -8-heatbed I bought one when they were first introduced and liked it so much I bought a 2nd one - both are on SD4s - no modifications needed - just remove the old silicone heater and apply the Hale (comes with adhesive already on it - peel the backing & stick it in place).)

I had looked at that but I wanted to try out a SSR and 120vAC heated bed.  Also the SMINI doesn't have a mosfet for a 12v heated bed.

Not necessary with a 120vAC heated bed but I designed a power supply box very similar in dimensions to the original controller box of the SD4 that is holding the guts of a 240w mATX power supply.  This is more than enough plus gives me 5v 2amp standby power for the raspberry pi / MKS SMINI combo I'm going to utilize.

PLA/PHA is closer to PETG in characteristics and not brittle at all.  It comes out with an almost matte finish and works well with sandpaper and other abrasive finishing.

My current plan is to utilize your corexy and slightly modify the original z. 

I think I can resolve the stability issues with the platform and modify it to take a standard PCB heated bed. 

If this doesn't work out plan b will to implement a z axis similar to the E3D BigBox with 4 linear rails and 2 6mm leadscrews.  I would move all the z motors and electronics underneath the machine at that point too.  A much larger scope of work that won't really buy me much additional build volume so I would prefer plan a.

To start off I stripped down my SD4, removed all the bushings, and primered and painted the frame satin black.  This looks pretty nice with the light green PHA/PLA from Meltink that I'm printing all the parts in....

If you want an excellent heat bed, don't bother with the PCB type - get one of these: https://www.printitindustries.com/produ … -8-heatbed I bought one when they were first introduced and liked it so much I bought a 2nd one - both are on SD4s - no modifications needed - just remove the old silicone heater and apply the Hale (comes with adhesive already on it - peel the backing & stick it in place).

I would also recommend you upgrade the power supply (supernight, also available at PrintIt) as the stock units are not very robust.

And PLA is not the best choice for printer parts - far too brittle and it will fail in a fairly short time (been there, done that)

I'm going to use a MKS SMini board that I got pretty cheap and fast from FolgerTech.  I'm also going to use an AC heated bed with SSR from MakerTurn on Tindie

I'll post pics when I'm done.

I think I can resolve the stability issues with the platform and modify it to take a standard PCB heated bed. 

If this doesn't work out plan b will to implement a z axis similar to the E3D BigBox with 4 linear rails and 2 6mm leadscrews.  I would move all the z motors and electronics underneath the machine at that point too.  A much larger scope of work that won't really buy me much additional build volume so I would prefer plan a.

To start off I stripped down my SD4, removed all the bushings, and primered and painted the frame satin black.  This looks pretty nice with the light green PHA/PLA from Meltink that I'm printing all the parts in.

I tweaked your corexy design a little because I felt that the motor mounts were a little thin for the weight. This also allowed me to make the endstop mounting more sturdy.  The little pieces were too brittle for me in PHA/PLA.  I'll also add a couple of braces beneath the stepper motors to help take the weight off the mounts.

For the carriages I simplified the left and right a bit so they're just one piece now.

Thanks very much for sharing and for including the solidworks source files.  This is making it so much easier to tweak and mod.

This may come together for me sooner than expected. I realized Folgertech is only an hour drive away

You do need to order and then pick up they do not have a retail store to browse though.
The kits are on sale for BF the ft 5 kit  is on sale for $425. 15 % off    I can send you the coupon code if you like . I have considered the FT5  and could likely be converted to core x-y without too much hassle.
Seems like a nice kit either as desisined or as a jumping off point for a custom machine.
Tin

And brucesdad13, now I regret not using black plastic and spraying the cabinet matte black while I had everything out. Because those renders looks sweet

I now have serious bed envy.  Some 80-20 laying around.  Time to get to work.