Idea: The Flyplotter

[rockyboy]

Toying with trying out kevlar fishing line instead of timing belt. The PrintrBot Simple (Wood) seemed to have good results with it. It would be easier to source locally than timing belts, noched pulley, etc.. If it didn't work it wouldn't be a huge investment lost.

May start some videos of the process.

I've had a Printrbot Simple wood model with the kevlar line and dremel sanding wheel inserts for the pulleys running for a couple years now - haven't even had to retension the line unless I was pulling something apart for upgrades. I don't know if it would do as well with the forces involved with CNC routing, but it should be just fine for wire cutting foam.

 

[JasonEricAnderson]

I was looking around at CNC machines and started looking at my Y timing belt path. It was a closed loop, with the ends anchored to the X gantry. This would have required a pully at the far end for the belt to travel over. Instead I'm thinking I can move the Y steppers onto the gangry bases and instead, run the length of the timing belt over a couple retainer bearings/pulleys. I could use eye bolts at each end that would both anchor the belt and allow me to adjust the tension of the belts easily. I'm also going to try and use the same angle aluminum and skate bearings for the gantry X motion but in a different configuration. This would make the bearings ride on one edge rather than angled and on the full surface. I think since the pen carrage will be much lighter than the whole gantry I can get away with this.

Edit: Just realized this is how the steppers are on the Mostly Printed CNC. (Duh!)

 

[jhitesma]

Edit: Just realized this is how the steppers are on the Mostly Printed CNC. (Duh!)

Yep, it's also a setup many of the openbuilds designs use. There's actually a name for it that engineers use...but not being an engineer I can't remember what it's called.

One thing you don't show in your drawing though is something to keep the belts from slipping off the pullies. MPCNC did this with fender washers on the bolts that mount the bearings...but they also used "Speed washers" (can get them from skate shops as well) between the bearing and the fender washer so the outer race of the bearing won't rub against the fender washer. Speed washers are just small washers sized to match the inner race of the bearing.

I didn't want to pay for speed washers, so I just 3D printed some slightly conical washers the designer of the MPCNC came up with that do the same job. The have a raised center then taper off.

 

[jhitesma]

Oh also, plan for some way to adjust the belt tension. They stretch out a little bit after some use which is more noticeable on longer belts. The MPCNC just uses zip ties to mount the belts - so you pull the ties tighter to snug them up. But I've seen some versions that use eye bolts or other setups. The teeth on the belt will mesh with them selves so you can make loops on the ends by doubling it over and putting two or three zip ties around it to hold the loop.

 

[Balu]

It's a type of rack and pinion mechanics using a belt for pinion.

 

[Michael9865]

I was looking around at CNC machines and started looking at my Y timing belt path. It was a closed loop, with the ends anchored to the X gantry. This would have required a pully at the far end for the belt to travel over. Instead I'm thinking I can move the Y steppers onto the gangry bases and instead, run the length of the timing belt over a couple retainer bearings/pulleys. I could use eye bolts at each end that would both anchor the belt and allow me to adjust the tension of the belts easily. I'm also going to try and use the same angle aluminum and skate bearings for the gantry X motion but in a different configuration. This would make the bearings ride on one edge rather than angled and on the full surface. I think since the pen carrage will be much lighter than the whole gantry I can get away with this.
View attachment 68587
Edit: Just realized this is how the steppers are on the Mostly Printed CNC. (Duh!)

I like your refinements.

 

[JasonEricAnderson]

My stepper pulleys and timing belt came!

I started taking measurements of my plans and realized that I need to refine some things before I get to much further. The steppers I had been using, just pulled from the Google 3d Warehouse, were not the right size compared to the physical steppers I have. So before I can go to the store and get my rails/mdf I need to recheck my measurements. That shouldn't take to long.







I think this about does it. Still need to design the pen lifter and I think the stepper will be mounted on some metal 'L' plate I need to fab/modify but I'm confident enough to start cutting (AKA buying and cutting). Note to self, need to get a tap & die set from harbor freight for the Y skates... and I think I'm going to mod some CAT5 cable for my stepper lines.

 

[Michael9865]

...Still need to design the pen lifter and I think the stepper will be mounted on some metal 'L' plate I need to fab/modify but I'm confident enough to start cutting (AKA buying and cutting)...

View attachment 69177

Instead of a solid plate to prevent slippage of the belt in the pulley and bearing area, fender washers may be a simpler and cheaper solution. I am really liking your design. Is the NYCNC on YouTube stepper, pen, and spring setup for the Z axis what you are thinking about?

 

[JasonEricAnderson]

Instead of a solid plate to prevent slippage of the belt in the pulley and bearing area, fender washers may be a simpler and cheaper solution. I am really liking your design. Is the NYCNC on YouTube stepper, pen, and spring setup for the Z axis what you are thinking about?

Good idea with the washers. Yeah, I've had the idea for this ratteling around in my head for a couple years and I just came across the NYCNC videos a couple of months ago. They've been a great validation that I'm on the right track with what parts to get.

I'm going to try and build the Y rail skates without having to thread the holes.

 

[JasonEricAnderson]

Skates!

I got the two skates built for the Y axis tonight. I picked up the better-looking aluminum angle rail at Tractor Supply Company. I'm standing there looking at the various sizes and debating if I should go with the larger, inch plus width or save some money, weight, and size going with the 3/4 inch. I had one of the bolt/nuts/bearings in my pocket (I'm a little smart sometimes) so I did a few eyeballing measurements and decided to go with the 3/4 inch.



I've got two 200mm lengths cut and sized up what looked like it would work for the placement of the four holes.







This, of course, happened after I tried eyeballing it on my first piece I cut where I had the holes to close to one another and I wouldn't have been able to fit a nut onto two of them. Like I said, sometimes smart. Having a drill press helped.


The bearings popped right in and I set it upon one of the lengths of uncut rail.



Not bad. They have a very slick and consistent motion and glide to them.




The ends of the bolts stick up just a couple millimeters above the sides of the rails but I'll just have to give the MDF some clearance when I go to mount these to the sled/gantry.

Progress!

 

[JasonEricAnderson]

Ordered the power supply today and I realized I should post what parts I've got so far and I had a small realization.

Parts:
Power supply
New DC 24V 15A Switching Power Supply Transformer Regulated for Cctv, Radio, Computer Project

Arduino*
Inland Uno R3 MainBoard

CNC Shield with Stepper drivers/heat sinks
Qunqi A4988 Driver CNC Shield Expansion Board for Arduino V3 Engraver + 4pcs A4988 driver expansion Board

Timing belts and pulleys
POWGE 8pcs GT2 Pulleys 20 Teeth Bore 5mm & 5Meters GT2 Timing Belt for 3D Printer Reprap Mendel Prusa

Stepper motors (x3)*
MCM Electronics Stepper motor - NEMA-17 size - 200 steps/rev, 12V 350mA

Bearings*
Mini Logo Precision Skateboard Bearings

Aluminum angle*
SOLID ALUMINUM ANGLE,3⁄4 IN. X 72 IN. X 1⁄16 IN

(Note: Anything with * next to it I was able to source locally so I didn't actually order them but I wanted to have links to everything. You may be able to source similar things at similar shops)

---

I went to Microcenter looking to get my third stepper and poof. They no longer had them in stock. I picked up a couple other items and just as I was about to head out I remembered they have a clearance/returns bin and checked there. Score, there was one and it was on sale. As I was holding this little stepper I got to thinking about the weight of using 3/4" MDF for the gantry. I'd chosen that material because I was modeling after the DIY CNC machines I'd seen all over my research but again, this thing isn't going to be holding a rotary tool and cutting wood. I don't need all that weight.

So I'm trying to find some good quality, flat, 1/2" plywood to use for the gantry.

 

[JasonEricAnderson]

I had a head scratching moment when I pulled the power supply out of the box and looked it over. I was thinking there would be a power plug port on one of the sides. There isn't. You wire up your own power input plug to the right most three terminals. They are clearly marked C for Common, N for Neutral and the "upside-down christmas tree" Ground symbol. I pulled a 'crazy 8' power cord out of a bucket, snipped and stripped it's leads and then tied an underwriters knot before hooking them up to the terminals.

Since I'm having problems finding MDF thinner than 3/4" I realized I may be able to just use a shelf from a wall shelf system for my gantry and side sleds.

 

[jhitesma]

View attachment 70628

I had a head scratching moment when I pulled the power supply out of the box and looked it over. I was thinking there would be a power plug port on one of the sides. There isn't. You wire up your own power input plug to the right most three terminals. They are clearly marked C for Common, N for Neutral and the "upside-down christmas tree" Ground symbol. I pulled a 'crazy 8' power cord out of a bucket, snipped and stripped it's leads and then tied an underwriters knot before hooking them up to the terminals.

Yeah, I'm not a huge fan of those supplies because of that. My Fogler 3D printer uses the same one (from the looks of it) and I added one of these: https://www.amazon.com/Inlet-Power-...&redirect=true&ref_=oh_aui_detailpage_o01_s00 Housed in one of these: http://www.thingiverse.com/thing:954451 so I could turn it on and off easier.

Though I'd warn those switches are not well made. Mine failed after a month or two and the replacement I ordered came in pieces (not broken, just disassembled)...but then the original started working again For the price it's hard to complain...but you do get what you pay for.

With one of those switches you get a fuse, a power switch and can use a standard PC power cord. If you don't have a 3D printer you could always just mount it in a wooden box or something similar. There's also this version which is a little more expensive but has mounting ears so may be easier to work with in some situations: https://amzn.com/B00ME5YAPK

Since I'm having problems finding MDF thinner than 3/4" I realized I may be able to just use a shelf from a wall shelf system for my gantry and side sleds.

Wow, finally something my local big box stores have that others don't! Both HD and Lowes here in town have 1/4" and 1/2" MDF as well as 3/4". Doesn't quite make up for them not having full sheets of pink foam and no fan fold foam though

 

[JasonEricAnderson]

I had another idea while trying to find some suitable MDF at Lowe's. I can use premade shelves. These are very flat, have a nice, white covering on most of the sides and it should only require me to modify my design just a bit.


Using a round file to countersink my rail mounting holes.


#6 screws (some flat some dome head) sit nicely just clear of the skate.


It's close but the skates glide freely past all the mounting screws.


I want to keep my pen holder assembly lightweight. For the first try I'm going to see how some simple plexi/acrylic will work.

 

[JasonEricAnderson]

I'll be documenting my progress with build videos.

 

[jhitesma]

Can't wait for more updates. Looks like you're just a few hours of work away from making an axis move under it's own power

 

[JasonEricAnderson]

 

[jhitesma]

Any further progress? Can't wait to see you cutting some foam with it