Reply with QuoteWhy are so many people worrying about dual Y-axis drives when most of the best built commercial machines do it that way and it is the cheap chinese machines that don't?
LOL, as long as you remember how you configured your coding in relation to your axis.
I tend to be very pedantic when it comes to engineering aspects, so for me it can only ever be....... X is left to right, Y is fore and aft, Z goes up and down and never the twain shall meet, except in circles where you start off going left then go right and end up going left once more and if you work with spirals you go in ever decreasing circles until you disappear where the sun never shines.
On the subject of the twin stepper gantry drive....I wouldn't do it that way....synchronised drive or nothing.
Ian.
Why are so many people worrying about dual Y-axis drives when most of the best built commercial machines do it that way and it is the cheap chinese machines that don't?
Beats me.Originally Posted by Art Mann
A dual axis drive system syncronized with Mach3 or LinuxCNC works so well that it has become a common way to build these machines no matter what drive letter a person assigns to it. Ian insists that he just doesn't want to do it that way. Doesn't bother me. He can build his machines that way if he wants to. I have two machines using ACME lead screws on one and R&P on the other that are as reliable as they need to be. I have run 8 hour 3D carvings with 60+ Mb gcode files and it goes right back to 0,0,0 each and every time the job is completed. The Chinese and/or Ebay didn't create any convention with respect to drive letter usage. There are common ways to do it for certain types of machinery, but there is no worldwide standards committee approved convention that rules how we all have to do it.
CarveOne
http://www.carveonecncwoodcraft.com
Why?.....because the cheap Chinese machines do not have dual drives....only single central screws.......only more expensive Chinese routers have dual drives......I may be wrong on that, but if you care to name a few "cheap Chinese Routers" with dual screw Y axis (gantry) drives it could be a clearer topic to be discussed.
I think the aspect of a cheap Chinese router with dual screw drives on the gantry is contradictory to being cheap.
Not many people buying a router on the forum are indulging in expensive commercial routers, unless they are involved in production which makes it a question of manufacturer's design.....they make it that way so you have to buy it that way, like it or not.
Before the Titanic sank nobody questioned the design of the ship in not having sufficient life boats for all the passengers.....it was assumed it would never be an issue.
Ian.
Interesting side discussion.
That is the important thing but I agree there should be some standard within the industry. Te problem here is that I've always referred to the gantry axis as the Y and the table X. Mainly because of the way most machines are operated which is from the side.
Which assumes you are standing at the end of the machine operating it. This isn't always the case and on really big machines the operator station will be on the side near the gantry.I tend to be very pedantic when it comes to engineering aspects, so for me it can only ever be....... X is left to right,
I have to tend to agree with you on this one I'd even go so far as to move the screws somewhat inboard to reduce the lengths of the belts if needed. On these forums there seems to be some negativity with respect to timing belts but they are used all over the place in industry with good results. Yes they are an additional expense but also less of a long term hassle.Y is fore and aft, Z goes up and down and never the twain shall meet, except in circles where you start off going left then go right and end up going left once more and if you work with spirals you go in ever decreasing circles until you disappear where the sun never shines.
On the subject of the twin stepper gantry drive....I wouldn't do it that way....synchronised drive or nothing.
Ian.
handlewanker, reread my post. People are claiming that the dual Y-axis drives are a flawed design, not that it is a more expensive design. That is a preposterous assumption when you look at how most of the best machines are made. If someone is looking for the cheapest way to build something, that is a different matter.
Hi, for what it's worth, I prefer the moving table fixed gantry router design, and that automatically indicates that a single central screw under the table drive will be used, but if I were to indulge in a moving gantry type it would have twin synchronised ball screws without a doubt, and I would contemplate modifying one that had a single central screw as I think it's a better way to do it.
Moving gantry routers are a compromise in machining capability when you are considering if it will machine anything harder than plastics or hard wood, possibly aluminium too but with some reservations on design build.
As this thread is a design perusal, all roads lead to Rome etc, and some are better paved than others.
I don't think I will be building a router in the very near future, buying one most probably if I get the urge to pawn a few of Granny's trinkets for a couple of coppers to finance one, but the design aspect of the various build structures has always fascinated me.
The road most seem to follow is usually one from lack of experience and facilities, engineering wise, lack of funds or lack of a place to build it and set it up to work it without messing the carpet or polished floors and annoying the other tenants with the late night noise of whining steppers etc, so the ideal design never really materialises when a DIY model is on the slips.
The difference is when you buy one you get what the experts decide is economical for the intended market, and one more nut or bolt can push it over the edge of the import duty, tax bracket, delivery structure, and a falling dollar does not help either.
I have fixed ideas on a design build, and whatever tickles your fancy is how you will prefer to do a build......the outcome is entirely of your own choosing based upon advice good or ill advised but definitely from the "consultants" ....FREE.
I will say that the current design on the board now is looking very promising, so to go forward is just a matter of choice..... in design nothing is impossible, only the outcome.
Ian.
Hiyyyyy, I come from the old school, and they fit spring washer to Nylock nuts to ensure the damm things don't vibrate loose.........answer your question?
There's no "flawed" about it........it's a sense of belt and braces in case the belt buckle pops off or a button on the braces falls off.
Mum always said "wear clean underwear in case you get run over by a bus"....LOL.
BTW, the manufacturers only give a warranty period for a short time, and "if" a stepper did fail, they will replace it......nothing else......you have to do the job over if it gets ruined, but it's very hypothetical.
I wouldn't say that adding a toothed belt and pulleys to synchronise the screws is cheaper than just twin screws and steppers....a bit more expensive maybe, but not extortionally so.
Ian.
thnkx
I figured to go with 3/16 (0.1875) thick tubes and a cheap mig welder with flux wire can go up to 3/16" , but I have a little experience with a stick welder as well , so i m going to leave the choice for the final stepBTW, a Mig welder does not have all that much capability for penetration, and you will probably get better results and cheaper too with a stick welder.........a Mig welder with more oomph will cost a packet along with the extras like gas and wire.
The tubing for the frame work will need to be thick wall anyway if it's to do it's job.
i think it s gonna be a separate framework to mount the machine on it .Is this going to be the final design layout for the router per se, or are you going to also have a base framework to mount it on so that it is a stand alone unit as opposed to standing on a bench?
honestly I didn't understand what you mean by jacking pointYou will need some jacking points under the base (6?) to allow alignment once the welding is complete........it will twist if not supported properly.(because of my english)
thanks for reply
if 380 oz-in motors can do the job , I would definitely go for gecko g540 ,but if i wanna go over 3.5 A and still wanna use gecko s drivers it s gonna be too expensive and i may have to rethink it
anyway any suggestion on ballscrews would be appreciated (2005 , 1605 , 1610 ...)
Hi Boof, by jacking points I mean at the bottom of the 4 corners and 1 in the middle of each bottom side you have jack screws that you screw out to align and/or level the frame once it's mounted on it's stand or a bench or the floor, whatever.
You weld nuts on the bottom of the frame, say 19mm or 3/4", at the 6 points I mentioned and have hexagonal headed bolts with lock nuts to lock them once the machine is level etc......they act like jacks to push the machine up or down as needed.
Without jack screws the machine will not sit firmly on a flat surface or one that is not quite level, like a bench etc.
On the welding side, you have to go with whatever method you feel comfortable with....preparation is important, such as veeing out the joints for the tubing ends etc, and an angle grinder is a must here to make bad weld seams good for re-welding.
Stick welding is usually a good starting point for a welding career and a box of welding rods can go a long way for little cost.
I currently use a plasma welder for all my welding jobs now, but when I was Migging in another life, before I bought my own stuff, I use to borrow a large reel of plain wire and a gas bottle from a mate of mine and pay him for the stuff I used.
Ian.
A few comments about welding:thnkx
I figured to go with 3/16 (0.1875) thick tubes and a cheap mig welder with flux wire can go up to 3/16" , but I have a little experience with a stick welder as well , so i m going to leave the choice for the final step
Mig or flux core welding can be perfectly fine for the sizes of tubing you are talking about, with one qualification, don't go too cheap on the welder. In this regard a welder in the 175 to 220 amp capability range would be the right size. Stick welding is just as good but the cheap welders are very inefficient. In my case I went with a Mig welder because the electrical service to my house literally would not support a conventional welder.
In either case precision fit up of the to be welded components is a must. It literally makes all the difference in the world when it comes to having the frame come out nice. By this I mean cutting parts to precise length, with square or precisely metered ends as required. The parts should be done in such a way that the frame can be assembled "dry" with clamps and look right with no gaps in the joints.
As to penetration I've never had a problem on steel tubing using either Mig or flux core. That really isn't an issue as far as I'm concerned.
At some point you either have to compromise or pay the money.i think it s gonna be a separate framework to mount the machine on it .
honestly I didn't understand what you mean by jacking point
thanks for reply
if 380 oz-in motors can do the job , I would definitely go for gecko g540 ,but if i wanna go over 3.5 A and still wanna use gecko s drivers it s gonna be too expensive and i may have to rethink it
anyway any suggestion on ballscrews would be appreciated (2005 , 1605 , 1610 ...)
There will always be compromises, regardless of design. The most obvious for the belt design is that it at least limits your options and at most creates complicatons if you decide to build a raised rail or portal design. There is also the issue of stretch which can create errors in backlash or lag; direct coupling eliminates such errors.
As to experience, my second and third machines featured a gantry driven by two screws, synched via timing belt. While it worked fine for what it was I could have done without the needless complexity. But there were some pros, like the ability to remove the machine from the base and position it on a large work pirce, such as a floor or door. The motor could have been bigger, and for a drive like a G540 it probably wouldn't be sufficent since a larger frame motor would have been ideal for the gantry, meaning a higher priced drive and larger power supply. Also, larger mtor = increased intertia, so performance can suffer a bit depending on the machine. I like the raised rail design for ridgidity, but you loose quite a bit of usable travel for the real estate as opposed to a raised gantry, and it makes feeding long stock through a challenge (I raised my machine on pads for such tasks.)
My small machine is a fixed gantry moving table design, which works great for the work size (14.5 x 8.5 x 5). It can be inconvenient to make one in large scale; my favorite would be CR Onsrud's Extreme Duty series beast-of-a-machine.
I finally settled on the dual gantry motors and raised gantry for my larger table for it's ease of construction, modularity, simplicity, and use. Your needs really should dictate the configuration of the machine
So is there really a right or wrong way? It's right to you depending on your budget, needs, and abilities.
Hi, In the last design release by Boof, the table has a through clearance as it is above the end cross rails.......there should be no problem with "loss of real estate" for long jobs etc.
The same goes for the table coverage in the width as the X axis travel and frame can be made wide enough to cover the whole of the table.
Having the X axis carriage wrapped round the bridge to give it rigidity also makes it difficult to have a narrow frame as the carriage must move all the way to the end of the X axis cross beam on both ends in order for the spindle to cover the table width, which means the frame and the X axis cross beam must be slightly wider.
BTW, It just occurred to me that on looking at the final frame design with the open ends it will be near impossible to couple the drive screws with a toothed belt if the table is to be allowed open ended clearance at the end for longish jobs.....so the twin screw design will be as normal and uncoupled, and hoping for no lost drive in one motor etc.
I have it on good authority (in the forum posts) that this scenario will never happen, but if it did, nothing would suffer from the consequences of one stepper motor drive loss, as the remaining stepper would stall against the loading of the other static screw drive.
The advantage of an open frame at both ends of the table for long jobs far outweighs the need for coupled twin screws.
This design could be simply modified, if the need arose for a moving table design, just by fixing the X axis cross beam to the frame sides and having linear rails and a single screw centrally placed beneath the table......the frame being made longer of course.
This has got to be one very versatile design and immediately lends itself to being made from off the shelf common square steel tubing......eat your heart out China, the end is nigh.....LOL.
For want of a better title I'll call it The Boof MG Router.....MG standing for moving gantry, or MT for moving table as applicable.
When can we expect work on the first prototype to start?
Ian.
thanks for replies guys and sorry for long delay , been extremely busy .
as for start prototyping , I can not wait for that but something came up and I really donno when I m gonna be able to start , unfortunately (for me) i may have to wait for maybe a few month ! anyway I ll be back as soon as I can , and will update this post if I change or start anything , mean while any suggestion on ballscrews would be appreciated ...
Regards
