Cherry Pi III Is Available

Hi Guys

Check out my new version on Thingiverse

[www.thingiverse.com]

Andy

Sigh...I *still* haven't quite finished printing CP Mk1, and you're already up to CP Mk3!

Seriously though, I like the evolution among the designs, and that you keep improving it where other designs have become stagnant. Keep up the great work.....

Hi Vreihen

I seriously think that's it now for Cherry Pi. It's a great printer, easy to build and relatively cheap. I've started to work on a new design now that uses the core XY transmission system developed by MIT. The prototype is up and running and I think it's the way to go in terms of low part count, small footprint and (very) high speed. The small, rigid frame gives very accurate prints and using a bowden on the X carriage means very low intertia, less even than a delta. My prototype is on Thingiverse ( [www.thingiverse.com] ). I still have some wrinkles to iron out in terms of the moving build platform, it's not as stable as I would like. That said the print quality and speed are the best I've ever achieved with any sort of printer. Not as cool to watch as a delta though!!!

Andy

Nice design, if not for the bolt heads you need to drill to fit the magnets.
Are there any alternatives to them, for magnetic coupling?

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Artlav
Nice design, if not for the bolt heads you need to drill to fit the magnets.
Are there any alternatives to them, for magnetic coupling?

They are really easy to do. I have a pillar drill and I made a simple jig. Just a piece of 3mm mild steel with an M5 hole tapped in it. I clamp this in the drill vice and can make a full set of 12 rod ends in about 15 minutes. I do know a couple of people that have used a hand drill and a normal vice. The 10mm ball end cutters are available for about £5.00 on Ebay. You only need to take a minute amount of metal from the head to form the cup for the 10mm spherical magnet. Looking round the forums I have seen other types of magnetic coupling and I've tried a couple. For me, the way I do it now is the best way.

Andy

I made two sets of 1/2 inch (~13mm) cupped rod ends using a cordless drill holding the rods in my hands with the cap screws installed. My CNC-grade ball end mill bit set me back $45 (tool truck price) since I went with 1/2 inch spherical magnets, but the process it self was simple and painless.

With that said, there is an ongoing research thread on the Google Deltabot forums now building on a gentleman from New Zealand's use of tensioned strings and rods with non-magnetic spheres on the end. The string between the carriage and effector plate holds the rods into their sockets, eliminating the magnets and end play at the same time.....

OMG I can feel a Cherry Pi IV coming on ....

For once, I may be ahead of you! I'm half way through printing the CP-I rod holders and effector plate, and plan to use some leftover 5/16" steel spheres from my Johann recirculating ball bearing carriage experiment to ride in the 10mm cups. I think that shock cord is the way to go, but we'll see once I have the last two rod holders printed.....

Pictures please :-)

Oh snap... atleast, it's almost the same part as the II (Most of change are the Printed Parts?).

I'll update my files for this one! Glad I didnt print already!

btw, I'll be using the OpenBuilds Smooth Idler Pulley : [openbuildspartstore.com]

Edited 1 time(s). Last edit at 06/02/2014 05:05PM by nka.

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- Sebastien Plante (nka)

Just FYI, if you want to use M5 to tap into the arm, you'll need 4.20mm (or 11/64?) drill bit (not 5mm) or use M6 bolt. If you glue them with CA, it will be okay. I ordered a 5MM ID Steel pipe and It's too loosen. I'll use M6 Bolts

Edited 2 time(s). Last edit at 06/02/2014 10:14PM by nka.

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- Sebastien Plante (nka)

I just like how clean and organized it is. If I ever build a Delta, either this will be it or it will be my basis.

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Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus

Andy,

What firmware do you use into the RAMPS? Marlin?

Also, I would like to add a 25mm (I took the mesurement of the Sunon MC25101V1000UA99) fan for the J-Head as it seems recommended for PLA. I would hook it only on the bottom (red arrow) ?



(SketchUp : [stuff.quebecit.net] )

Does it make sens to you?

I'm asking cause, since I dont have the printer yet, it's hard for me to figure how it will fit. Plus, it will be printed in ABS and I wont be able to do it with the printer.

Or something like this, were I could "clip" the fan?



Edited 3 time(s). Last edit at 06/04/2014 03:04PM by nka.

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- Sebastien Plante (nka)

I'm curious as to how you machined the bolt heads with the ball head mill.

I was looking at magnetic arms for a MK but they used cylinder magnets in the arms with steel balls on the effector and carriage.

Your way seems cleaner to me since it seems like it would have more surface area for the the attraction between the parts and be easier to assemble. I have a feeling my MK will be busy making parts for one of these once I get it going. I wanted to scale up to a 250mm build surface and 2020 extrusions anyway. Would the Misumi 2020 be an adequate substitute for the Bosch/Rexroth extrusions? I already have some 360mm and 750mm handy.

Edited 1 time(s). Last edit at 06/04/2014 03:30PM by WZ9V.

I dont where I read that, but he used a steel plate with M5 taps. Placing the bolt into the tap and them using a column drill with 10mm drill bit doing a small cup hole. I'll be doing this next week (or maybe Friday). I'm currently doing the M6 tap into the pipe.

And I hope Misumi 2020 are working, cause this is what I've ordered!

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- Sebastien Plante (nka)

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nka
Andy,

What firmware do you use into the RAMPS? Marlin?

Also, I would like to add a 25mm (I took the mesurement of the Sunon MC25101V1000UA99) fan for the J-Head as it seems recommended for PLA. I would hook it only on the bottom (red arrow) ?

f5H0vdq.jpg

(SketchUp : [stuff.quebecit.net] )

Does it make sens to you?

I'm asking cause, since I dont have the printer yet, it's hard for me to figure how it will fit. Plus, it will be printed in ABS and I wont be able to do it with the printer.

Or something like this, were I could "clip" the fan?

26xeZ7l.jpg

Hi Sebastien

I use Rich Cattell's version of Marlin as this has a great auto calibration function. As far as the fan goes, I have never needed one for my Jheads but if you use one just attach it to the effector with a dab of high viscosity CA. It's great stuff. You may find that the effector magnets stop the fan from turning. Some fans seem more susceptible to this.

Andy

Edited 1 time(s). Last edit at 06/04/2014 06:04PM by AndyCart.

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WZ9V
I'm curious as to how you machined the bolt heads with the ball head mill.

I was looking at magnetic arms for a MK but they used cylinder magnets in the arms with steel balls on the effector and carriage.

Your way seems cleaner to me since it seems like it would have more surface area for the the attraction between the parts and be easier to assemble. I have a feeling my MK will be busy making parts for one of these once I get it going. I wanted to scale up to a 250mm build surface and 2020 extrusions anyway. Would the Misumi 2020 be an adequate substitute for the Bosch/Rexroth extrusions? I already have some 360mm and 750mm handy.

They do work really well. I made a simple jig out of a scrap piece of 3mm mild steel bar. Just tapped a M5 hole in the middle of it. The steel is then clamped into my pillar drill vice. I put a 3mm round rod into the drill chuck and line it up so that it goes into the Allen socket of the M5 SHCS. I use BZP screws. Once the screw in the jig is lined up with the centre of the drill chuck I replace the 3mm rod with the 10mm ball end mill and just unscrew the SHCS when it's been milled and screw in another, etc. takes about 15 minutes to do all 12. The edge of the 'cup' is sometimes a little bit sharp so I normally smooth it's edge on my scotchbrite wheel as well. Dead easy. You only need to mill to the edge of the knurling on the screw head and this leaves half of the Allen socket free so you can use an Allen wrench to self tap the rod end into your 5mm ID aluminium tube rods.

Andy

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nka
Also, I would like to add a 25mm (I took the mesurement of the Sunon MC25101V1000UA99) fan for the J-Head as it seems recommended for PLA. I would hook it only on the bottom (red arrow) ?

f5H0vdq.jpg

The original Thingiverse part that is the base for Andy's revision actually had the holes for screwing an E3D hotend fan onto the side in that location. It apparently was lost in the conversion to J-head.....

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WZ9V
I'm curious as to how you machined the bolt heads with the ball head mill.

I used 1/2 inch (~13mm) spherical magnets on my printer, with a 1/2" ball end mill bit in my cordless drill. Health and Safety be damned, I put the M5 SHCS's into the rods, held the rods in front of the drill, and pushed by hand until they were milled to a cup. Since I used black screws, it was easy to see how deep that I was cutting since the cup was shiny metal and the remaining cap was black. Just keep milling until the silver reaches the edge of the head, and that's it. There's no reason to mill any deeper. I did 24 screws on one 18V battery charge with energy to spare.....

Thanks, sounds like I could easily do it with my drill press based on the descriptions.

The hardest thing was getting the ball end mill bit. I paid local auto mechanic tool truck price for my 1/2" bit, and my cost per screw is down to $1.50 each after three sets. Andy had much better luck finding a 10mm bit on eBay for much less money.....

The sad part of this Endmill is cost vs usage. I dont think I will ever use that again !

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- Sebastien Plante (nka)

Sell it to another RepRapper or on eBay when you're done.....

Yeah, I mostly will do this. Or sell pre-milled bolts and magnet as a package. I will have too many of them anyway !

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- Sebastien Plante (nka)

Hi Guys

This is the one I got [www.amazon.co.uk]

Andy

Andy,

Seems that the Extuder Body isnt "flat" on the surface. With Cura, you can do "Lay Flat", but not with Slic3r or Simplify3D.

I dont have the SketchUp file, can you just align it and reupload?

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- Sebastien Plante (nka)

Hi Sebastien

Mine was fine. I will upload it again though. Maybe a rogue file slipped through.

Will be sometime on Sunday

Andy

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AndyCart

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vreihen
For once, I may be ahead of you! I'm half way through printing the CP-I rod holders and effector plate, and plan to use some leftover 5/16" steel spheres from my Johann recirculating ball bearing carriage experiment to ride in the 10mm cups. I think that shock cord is the way to go, but we'll see once I have the last two rod holders printed.....

Pictures please :-)

Here are the results of my failed experiment. My current Delta RepStrap uses 1/2 inch (12.7mm) spherical magnets with cupped steel SHCS on the ends of the rods as the sockets. My initial thinking was that I was going to toss some leftover 5/16" steel spheres into the CP-I's effector plate sockets loose, then put my current rods on top of them for testing. Sure, there would be slop, but it was only a proof-of-concept. I changed my mind, and decided instead to use CA to attach 1/2" plastic spheres to the sockets using CA instead, and then use my existing rods on the plastic spheres.

Here is the effector plate with spheres hanging from a shock cord to each carriage (note the CP-I upper bracket):



Getting two rods in was relatively easy (the blue painter's tape is holding a bit of wax paper under each screw for lubrication):



After the third rod, the effector plate kept wanting to twist from the shock cord tension, so I had to dedicate a hand to holding it straight from then on. On multiple attempts, I was trying to insert rod #5 when one of the others would fall out and hit the floor. Since that meant letting go of the effector plate to retrieve it from the floor, I had to start over from scratch. I'd post pictures or video, but you can Google "keystone cops" for a better slapstick comedy routine.

Long story short, one of the major benefits to magnetic ball joints as used on the CP is simple effector plate and hotend maintenance. I can have the effector plate off in 15 seconds, and back on again in 30 seconds. Even with quick disconnect hooks on the shock cord, it is darn near impossible for one person to get six rods in place using a non-magnetic, tension-based retention system. It can probably be made a bit more simple by using deep sockets with the spheres attached to the rods, or maybe by crafting some removable rod holders for doing the installation. I'm at the point in my life where saving a few dollars by not using magnetic spheres isn't worth the hassle, and will be ordering another batch of 1/2" spherical magnets for this new effector plate as soon as I post this message.....

Oh well. It's fun trying new things. Like you I've decided it' easier to just buy the magnets. Currently I'm getting them as a block of 64 from China for about £16. They are marketed as an executive toy but they are just 10mm neodymium spheres so perfect for our needs.

Core XY kinematics has me hooked at the moment. Very promising in terms of print quality and speed.

Andy

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AndyCart
Oh well. It's fun trying new things. Like you I've decided it' easier to just buy the magnets. Currently I'm getting them as a block of 64 from China for about £16. They are marketed as an executive toy but they are just 10mm neodymium spheres so perfect for our needs.

If I did not have $50 USD invested in the 1/2 inch ball end mill bit, I would be converting to 10mm spherical magnets. When I went to re-order last night, my source for $1.69 magnets no longer carries 1/2" and does not expect to stock more! I had to pay $2.49 each from a second source, with the third source being an insane $3.66 each. If I wind up doing a third printer, it will be on 10mm toy magnets and I will have the buy a new bit for cutting 10mm cups.

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AndyCart
Core XY kinematics has me hooked at the moment. Very promising in terms of print quality and speed.

At this point, I just want to get a stable Delta printer working! I thought that I would be half way through printing the airfoil mold "bucks" that started my foray into 3D printing, and so far all that I have to show for it is a pile of printer parts and scrap plastic. I'm afraid to look at Core XY right now, because I might get sidetracked again.....