My Y axis was also stiff. I just added two eccentrics, i.e., replaced the spacers, on the other two wheels. Of course, you will need to drill out the original holes, I forgot the drill size. Took some time to adjust all four, but it made a huge difference.
Rick Harms

 

A vacuum hold down is easy and cheap to achieve with MDF, some PVC pipes and valves and a shop vac. I divided the bed into 4 zones which can be individually activated by the valves. As an extra I inserted threaded kind of t nut into the vacuum holes. Now I can use either the vacuum hold down or bolts and hold down blocks to keep the workpiece in place. It works great.

BTW. Running my Buffalo almost daily now, sometimes for more than 10 hours (!) continuously and having no issues at all (knock on wood). Precision is still within 0.05mm after months of hard work. I'm very satisfied with how it all turned out with OB materials. Keep the good stuff flowing, Mark!

 

in this v wheel kit dose it come with the bolt and nut

 

and a nother thang in the first video it say use a 10mm screw on the z-axis i dont see the 10 mm screw listed in the parts list but i do see the 20 mm need help ordering parts today to start build

 

hello i need to no what size eccentric spacer to use it dosent say 6 mm full size or 1/4" full size

 

oky thanks i,ll use the 1/4" ones and thanks for the reply iam new will have lots of ? lol

 

well guys and gals i reseved my first shipment of my very first OX build parts . just thought i would let all no about my progress have to order more soon.

 

If Ex music teacher Steve of Clayton, Australia is listening, give me a call..

 

My Small Ox kit has arrived and the build has begun.
My main problem has been finding the dimensions for the build I don't know if I am right, but I have resorted to using the tape measure found in sketchup. I am guessing that is where the sizes are hidden, I have had to go by the videos to identify which size bolts bolts go where.
Having watched the build videos, I decided to assemble all the wheel/bearings first. When I mounted them on the plates and tightened them, I found they felt very rough when turning, almost as if the balls had flat spots on them. I missed the bit where a shim needed to be installed between the bearings!! Sure had fun getting the bearings out of the wheels, but managed to get the problem sorted now they all turn nice and smoothly.
My next problem was the lack of 10mm screws in the kit. The 8mm screws did not provide enough threads to hold the acme block securely enough in my opinion, so I used the 15mm.
Today I tackled the job of cutting the X axis beams to size. First stop, Bunnings to get a good blade for the compound radial saw. The 30 tooth wood blade would be asking for trouble. Fitted the new blade and made test cuts on timber to set up a perfectly square cut. Since the V-Slot 20x60mm was exactly 1000mm, there was going to be no way I was going to get a 500mm cut. Anyway I made the cut and checked for square.
Ahhhh!!! I ended up with the worst cut I have ever seen!! The bloody blade had come loose!! Reset the blade and carefully trimmed millimeter by millimeter and ended up with a near perfect finish, the final length being only a couple of mm smaller than I had planned, but all looking good. The new blade cut like a knife through soft butter, a good investment I would think. Then came a couple of hours of tapping... I had forgotten how much I hated hand tapping threads during my apprenticeship days!! But it passed the time while hiding out in the shed, away from the reach of missus and the grand kids.
Next problem was that I had set up the Z axis wheels for the 20x60mm V-Slot, as per the video. Bugga!! No more 20x60, so had to disassemble the the Z carriage and reassemble for the 20x40mm V-Slot. All good everything moves smoothly and looking good. I may have to get another length of 20x60 V-Slot at a later date if there is too much flex.
I then threaded the acme rod through the acme nut block, and mounted the Nema 17 Stepper motor. Now a new problem has reared its ugly head. The bearings will not fit onto the acme rod. They will only go on about 10mm then jam up and no amount of persuasion will allow them to go any further. The same situation exists at both ends of the rod. It is at this point I gave up for the day.
Looks like I will have to rig up the power drill tomorrow and very carefully reduce the diameter of the acme rod so it will fit into the bearings!
Apart from that the first days of construction seems to have gone pretty well.

 

Sand the bearing ID, not the ACME rod

 

Hi guys, in Australia there is a store that sells v-slot up to 2.4m, I was wondering if it would be possible to do essentially a standard OX, but in a 2.4x1.2m size, or would the flex/deflection become too large for the standard OX design at that size... And if so, what would be the largest size OX one could build? thanks

 

I'm current my only in very early stages of developing the concept.. But the main capability I want that size for is to be able to use (metric) full size sheets in it so the c beam is not an option until it is made in 1.2-1.5m lengths.. At this point I would likely end up making custom plates anyway so I could Always use more/larger sections of v-slot

 

Where can you get a OX Kit. complete. looking for one that can do 4' x 4'

 

True words, Gray. How often does one cut full sized plates? Had this discussion with a friend here, who owns a Chinese 1325 and was telling me the Large OX would be too small. So I asked him how often he cuts full sized plates. "Ehhh, at best a couple of times per year cutting some decorative panels for a wedding or show". For the rest it is all 2/2.5D/3D work on smaller scale.

For those couple of times per year I just slide the full sized plate under my Buffalo (along the X) from the side and do the work in 3 sessions, moving the plate for the following session. I can engrave/2.5D/3D full sized doors (210x90 cm) by sliding them along the Y axis over the bed. All easy as pie.

Hell, if you really wanna go crazy, put your OX on top of a 2 x 3 meter plate (or bigger!), clamp it down and start cutting/engraving. Move it for the next part. Make sure it is aligned and use reference holes to stay on it. Can't do that with a big heavy production machine!

 

Quite true, most of us wouldn't cut at the size of a full size sheet very often (if ever)... However the one thing still left unsaid is the material usage efficiency (if you're buying full sheets) of being able to cut straight out of a full sheet rather than having to cut down your full size sheets before working with them which leaves you with lots of (hopefully) small offcuts which are near useless for anything other than your local scrap metal yard..

And yes, having a smaller machine with a larger table is a cost effective way of achieving it, but for the sake of a couple of meters of v-slot, (if you have the space) you might as well make your cutting area (y-axis) longer

 

Over that size sheet you also need to consider if you don't mind walking away from the cutting job. personally i do my best to avoid it, but an ox that size will have a maximum plunge of 3mm per pass and by sheet i expect he's talking about sheets of 18mm thickness, so even with a modestly detailed 8x4 sheet, you looking at a 10 hours + per sheet.

 

Hi,
a big machine is possible, using of course custuom plates and a lot of strenghtening.



The y-beam is a 200x80 heavy extrusion and probably costs more than an ox by it self.
As seen, it is ok to cut flat material but do not think it won`t bend along y , so 2,5D will suffer accuracy.
Also the plates to attache the wheels and y-beam are quite small, so cutting something heavy like aluminum will make it "tilt" forewards and backwards ... at least the wheels will suffer quite a lot while usage.

Possible - yes
makes sense??

greets

 

Could you elaborate about how you came to the 10 hours+ work on a full sized plate of 18mm with a DOC at 3mm? What kind of work you're talking about? Cutting only or 3D work?

 

Sure, mathematicaly it does sound extreme and doesn't equate so if I try to do it mathematicaly there's too many factors to make realistic, but for instance I recently cut a 8x4 sheet into a set of shelfs 18mm thickness at 9mm doc on a non oX. the shelfs consisted of 7 rectangles with keyed mortise and tenon so there were small keys to cut and all dog bone fillets were drilled, however all 2d and fairly undetailed. I cut it at 4m/min at 9mm doc with a single full depth finishing pass. Total time was just under 3 hours. An hour or roundabout was drilling.

In fact I have a time lapse video of it here:



So at 3mm doc would have taken 7hours at 4m/min. An oX will do 3m/min so that and a sheet of smaller parts you could easily be looking at 10 hours plus

Mathematicaly this doesn't add up, I've estimated the total circumference of all the parts at 12m with 3 passes the contour adds up to 9 minutes at 4m/min. But it's never a reality, if you looking for a good finish your going to want to slow federates at internal corners, you have the ramp or helix moves, adding tabs, finishing passes and the list goes on, all adding up.

My 1.5x1.5 oX regularily does 5 hour 2d jobs.

I think an 8x4 3d part you would be talking in days not hours

Not saying it's not doable, just something to consider

 

I agree, if your going to this extent. You would do away with wheels and use hiwin carriages.

 

I started with a Shapeoko hardware kit a little more than 6 months ago and decided that I'd expand the kit to 3"x4" (x,y) and because I didn't listen to (or really understand) what I was thinking about, I ordered a 1.5kw spindle and VFD to power it. By the time the spindle arrived I had finished the Shapeoko and discovered that the two had no business being mated together. A quick order of a 300w Quiet Spindle and speed control got things cutting, but the fun was just beginning. When I saw the twist that the 3' X axis had as it loaded up tool pressures, I knew that the spindle was not my only mismatch.

I finally achieved some ability to cut by bolting a 1/4"x1.5" steel flat between the two extrusions. It wasn't great, but it would cut without winding the x axis up like a rubber band in a kids toy airplane.

About this time I found Open Builds. Thank Goodness! It didn't take too long to educate myself to about the 3rd grade level - just enough to KNOW I'd started with the wrong build to start with, the wrong spindle and to some extent the wrong software too. With a desire to not build something that was too wimpy to cut what I wanted too, I started exploring some other options to build a souped up Ox which I documented here in Open Builds. It was recently completed and I'm happily cutting away with it at this very moment. I still need to post the final build pics, but it's working great.

My Shapeoko was pulled apart and the extrusions replaced with the ones that came in the kit and with the much shorter x&y axis it cuts much, much better. My son now has it and in a recent conversation he asked me about expanding it so that he could cut bigger material. I reach around the corner of my bench and pulled out 4 v-slot extrusions and plates I had already cut to build a 2 1/2'x 5' Ox.

He's 35yo, but he's still my son and bigger IS better - sometimes.