The Hox

Hi There..

Thought id post this idea i have rattling around since the cbeam came available for what i believe could be the strongest ox yet. I'm undecided about building another at the moment as i simply don't require another but thought id share the idea.

The design is pretty rough but the fundamentals are there. Design below is 1500 x 1500 - cutting area something like 1250 x 1250






Motor and belt need to be offset from center to avoid rubbing on the mini vwheel, the standard motor and idler wheels would work, just need to remove a corner to fit.

You cant see very well in the images but all the axis motor mounting, belt and idlers are the same. Only on x the mounts pass through the y gantry plates.






I haven't added any profiles to bridge between the ends of the y profiles as i believe with this design simply bolting to a solid bench into the feet from the underside with some care would work to the same effect

 

Adding some caps to over the idler wheels and pulleys would smarten it up. All pretty feasible stuff. I have simply duplicated the x axis assembly and used them for the y and left the gantry plates in-between the y gantry plates. these could be incorporated into the plates themselves instead. Im just lazy. or alternately If you were looking for something just to cut panels, you could even do away with the larger gantry plates completely and sit the x on the y runners, giving you 90mm of z travel

 

Yeah this is one thing I'm unsure of how well the pinion and idler performs set up like this, something I was hoping people with experience would comment on.


What ever the solution, I thought it would be nice if the x and 2 y's were all identical in assembly.

 

Cheers mate love to see someone build one a publish it. Hint hint.

I'll be expecting royalties mind.

Jokes

 

Ooo just thought of an even neater solution. Mounting the motors vertically between the gantry plates. I'll get a model up

 

Looks good.. My only suggestion would be to shape your gantry plates so they are wider at the bottom to allow you to spread the v wheels further apart and improve rigidity.

With the motor being used in this arrangement i would go for having the motor inside the c beam but add some mini vwheels to run on the bottom inside slot, That way you can run your belt underneath the wheels in that slot and loop over the pinion in the same manner as the original ox design.

 

just spotted thats what you have done in which case go with that one. It will be better balanced than underneath.

 

Ahh ok. 8" is okay it's the height that has given me a false perception. Why is it so high?

With mine i chuck multiple spoil boards on the bed dependant on what I'm cutting, but I aim for 50mm travel from bottom of z assembly to top of stock. Unless I'm using drills or long bits then I take them into account.

It's a pain but helps reduce deflection massively.

 

Look forward to seeing your cable management, aspheticaly not easily achievable. So be interesting to see.

 

Max travel I've settled with on my non ox which is 250kg of highly braced and very rigid aluminium x gantry with linear rail for x and z is 220mm. Any more than that you need steel imo.

I feel this is the max travel where rigidity would be compromised if I were to plunge further.

Really just depends on what you want to do with it. You build these things to cut a particular product really. I have left my ox with the standard length of travel but raised the bed which is fine, but I have cut parts at full plunge and now compromised the rigidity in my machine doing so.

So if you cutting foam all day and need extra travel, go for longer travel, if your cutting wood and composite panels all day you want the machine as rigid as physically possible so have the travel low eg 100mm.

If you do decide you'd prefer more travel to be more versatile, using multiple spoil boards can work well. Just keep in mind that a harder material at a distance of more than a 100mm could effect the rigidity of the machine. And won't be as rigid as a lower machine.

See a lot of designs with long z's popping up. task specific design choice is always going to better and not based on what would be nice.

 

my non ox design for hard composites, plywood panels and aluminium. initially designed so i could lower and raise the y profiles with max z travel of 250mm. Performance decreased at anything more than 220mm so now are fixed to welded supports. The aluminium profile used is heavy weight 10.5kg per meter 90x90 so gives you a rough idea what these things are up against.

At a guess If you were to say this is 10 times more rigid than a standard ox the optimal travel would be 22mm max, but this has a larger spindle capable of 18mm doc, the standard ox optimal doc is 3mm which is 1/6th the doc. so 6 times 22mm is 132mm which as it happens is a pretty good height id say, if you were to go with a 1kw spindle you may say that at ox is capable of 4mm doc and to better your chances you would subtract a 1/6th to 110mm. Not exactly scientific but best i could come up with.

Some pretty rough old spoil boards on there in that pic.. i normally use 2x 22mm + 1 x 18mm mdf on there.

 

yes you may have an issue with the slant.. you could just move the slant to start above the wheels. that may work. what i did on my ox which made a big difference is have another plate on the inside of the plates, square hole through so the x profiles go through it at the top and a block just above the wheels to space it parallel, and going down to the top row of vwheels with the vweel bolts going through both plates to stop any flex in the wheel bolts. seem to make things much more rigid.

Originally the design was std plates either side of y profile square sloted through as above, but i decided i didnt want the y profiles floating so i cut the inside ones and that gave the arrangement im talking about. worked well. not very apathetically pleasing but thats where most people go wrong.. it doesnt matter what it looks like its how well it cuts and youll find people that try to make it look pretty end up making un asphetic modifications that if they were designed for originally would have looked better anyway.

instead of a full plate this could just be a block on the inside of the plates with another plate bolted to that hangs over the ends of the vwheel bolts, that would most likely look neater in some nice polished ali.

But other than that the h beam and x carriage look good,

 

Hmmm, I'd say the original plates cog was front heavy anyway. It would be hard to measure but suppose you could try assembling the x + z + gantries and use fishing scales hooked on front and back or balance on a rod to see which way it goes.

If it falls back just add some more Ali to the z or vice versa.

In regards to the bolts yes just secured anywhere heigher or at the x profile with corner brackets and at the bottom with the vwheel bolts. Or simply a block bolted to the inside with a plate that has holes for vwheel bolts.

 

Yeah you could do that, inventor will do it also. Most likely Catia but not sure about the rest.

Means getting all the grades of aluminium set up and weighing any parts to get it spot on but would give you a rough idea without doing this.

Good idea.

 

Looking much better.

By the the double plates all that would be achieved by it is supporting the vwheel bolts on top row at both ends, so it wouldn't need to be a plate. It could be two 12mm thick bars one horizontally and one vertically bolted together to make a L shape say this - represents the wheels it would look like this L- rotate that 90 to the right and bolt to inside of gantry plate.

This may be a little ocd, it something that would pretty easy to do as a later addition. Actually thinking of milling some blocks and selling with wheels installed in them. the arrangement made a big difrence for my ox as those bolts do flex left unsupported. It seemed to happen in mine over time like they suffered fatigue.

 

I will get a cad model up of a block that will work to the same effect, when I'm back in the office on Monday.

 

Mechanically I can't imagine it makes much difference except you'd be adding a bit of weight to the z with the cbeam the opposite way

Suppose the upside to having the cbeam bolted to X gantry plate is you then have something to attach the cable carrier to.

But then the otherway round would provide better chip protection for the lead screw.

So you could say bolt the cbeam and use brushes to keep out chips or the other way with an additional Cable Carrier mount