Reply with QuoteMost likely not very robust. The motor is not really designed for axial thrust load.
Bluecarve ballscrew design
What is your opinion on this ballscrew design being sold as a hobby machine , no support or thrust control on any axis ?
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Re: Bluecarve ballscrew design
Most likely not very robust. The motor is not really designed for axial thrust load.
Jim Dawson
Sandy, Oregon, USA
Re: Bluecarve ballscrew design
Like Jim says. The ball screw will have a lot of play in it along its long axis; cutting forces will be able to push it around, so expect poor cut quality and forget about precision. But it's a lot cheaper to do it that way than to have to provide all those bearings and such.
[FONT=Verdana]Andrew Werby[/FONT]
[URL="http://www.computersculpture.com/"]Website[/URL]
Re: Bluecarve ballscrew design
It seems to have the same setup on every axis including the Z
Re: Bluecarve ballscrew design
It works good enough to sell the machine. After a while it stops working, then you need to replace the broken motor and redesign the ballscrew mount.
Re: Bluecarve ballscrew design
I was considering purchasing this machine as well, but down seeing these issues I'm having second thoughts. I'm very new to all this, would you be able to tell what is should be looking out for in the ball screw to get a machine that can be robust and have good cut quality?
Re: Bluecarve ballscrew design
The ballscrew coupling end must have bearing block...
http://free3dscans.blogspot.com/ http://my-woodcarving.blogspot.com/
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Wow as the maker of the BlueCarve range of CNCs that I'm flattered that there has been attention around my design. Let me put this to bed so that everyone can learn a thing or two.Originally Posted by delco
The reason for the exclusion of a support block is for maximum cutting area for minimum overall footprint. From my experience and reading of literature on ballscrew supports, I see the only benifits being for achieving higher rapids for longer ballscrew lengths and laziness in aligning stepper, coupling to screw. There is no significant force applied back to the stepper. The applicable acceleration rates are so well balanced that we are able to achieve <0.1mm backlash values and 0 motor failures apart from DOAs.
I'll share some numbers ????
130 Turbos sold in 2020
0 stepper motor failures (except for the 2 DOAs)
1500x1500 ballscrew combinations achieving 9m/min with 150mm/s/s acceleration with <0.1mm backlash
1000x1000 size achieving 13.5m/min (we reduce to 7m/min for the common folk)
Trust me, I wouldn't be in business today if I had any issues with such a design. Would a support help? Yes! But it would help if you are lazy in your design or want to achieve higher speeds or a combination. We don't have that issue.
I see the designs that my competitor use in their glorified 8mm all thread (lead screw) needs to be mechanically pulled to be able to achieve above 4.5m/min due to whip. So yes! You will need to support that stepper to avoid serious damage and serious under performance. To say that this design is superior is a huge joke. Good on em, I guess they need that to get somewhere through put down of others.
So from what I've been told they don't use the "motor failure" line any more and moved onto "not having a anti back lash coupling creates back lash". By the way these are the same guys that use two opposing PLASTIC "anti back lash nuts" that need to be regularly adjusted to compensate for wear. When are the put downs going to stop?
Anyways, we are a small Australian based manufacturer that has a strong customer focus and believe we have the world's best value CNC. An assembled 1x1m rail sized Turbo sells for $2,200USD, hence why we built 130 in 2020 alone and continue on strong in 2021.
To back up my claims, we give an indefinite parts warranty period (within reason), free lifetime return back to base full refurbishment any time you want and awesome customer service.
Cheers, Adam
Re: Bluecarve ballscrew design
Nice for the proprietor to respond.
I wouldn't say laziness is the major factor for using bearing blocks. Mounting directly from the stepper seems just the same to me in terms design and implementation. If anything easier. I'd rather not put axial load on my steppers. Maybe under light loads and casual usage bearing blocks are not required like so many 3dprinters but under years of constant heavy cutting forces I'm sure you would notice increased backlash. A bearing benefits are two fold, they last longer and are cheaper to replace. Beside at 1000x1000 or larger is the loss in travel relevant considering common sheet material sizes?
Nothing wrong with "plastic" backlash nuts. My set of self adjusting delrin nuts have performed very well over the years. I cannot notice any wear. Perhaps "theirs" is junk but I wouldn't know first hand.
I agree, 8mm leadscrew sucks. For short travel like the Z it's ok.
13.5m/m is ok for rapids but what cuttings speeds and amount of material can you remove while maintaining acceptable deflection?
I do like the extrusion builds. So clean and easy to assemble.
Cheers.
There is little to no axial load. Once again I'm flattered that you think my machines are capable for industrial applications. You'll find that a good chunk of machine makers out there do not employ a support block. Case in point an Axiom CNC, sold for 3x the price of a Bluecarve Turbo, does not have a support block. I've attached a picture for reference. I've been making the BlueCarve Turbo for a while and some of my customers flog their machines daily. One customer cuts 12mm aluminium for F3 racing support components another cuts 32mm thick spotted gum, 6m/min most days. The only component that failed was the guys Makita trimmer after cutting that spotted gum. He has since moved to a 2.2kw water cooled spindle and hasn't looked back. If there was an issue, I would have know about it by now.
Re: Bluecarve ballscrew design
I don't think anyone was suggesting using your platform for industrial application. I think you will find a good portion of members here are industrial cnc professionals and offer comment based on best practices and experience. I'll take that advice any day and try to apply it where possible.
I'm certain these machines are excellent for the intended market. They allow people like myself an opportunity into cnc with reasonable quality an cost. Your platform doesn't have bearing blocks and that is ok as your sales numbers validate. I'd still rather have them and would it definitely be a point of focus if I was in the market for turnkey solution. In no way am I saying your product is inadequate, if anything the opposite.
I am certain of this as well. If it can go wrong it will. Running a business is not easy.
Re: Bluecarve ballscrew design
Two wrongs don't make a right.Case in point an Axiom CNC, sold for 3x the price of a Bluecarve Turbo, does not have a support block
Any small machine under $5000 is making compromises. It's as simple as that. You can't make a perfect machine for $2000. There's nothing wrong with that, as long as people know what they are getting. Otherwise, very few people would own CNC machines.
Gerry
UCCNC 2017 Screenset
[URL]http://www.thecncwoodworker.com/2017.html[/URL]
Mach3 2010 Screenset
[URL]http://www.thecncwoodworker.com/2010.html[/URL]
JointCAM - CNC Dovetails & Box Joints
[URL]http://www.g-forcecnc.com/jointcam.html[/URL]
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
Re: Bluecarve ballscrew design
Good time to update this thread with real world experiences. So going on from the OP (who by the way is a supplier to a competitor here in Australia who tried to put down the BlueCarve name which by the way you can trace his user name back to his real name.... cheeky cheeky), that after selling >300 units and going strong for 4 years it seems like having no motor block has had no impact to it's performance with 5 motor swaps (more so DOA than this perceived eventual motor failure BS). That's a 0.4% ish percent failure rate (5 / 1200ish total motors).
What we have done is served the consumer clientele here in Australia with a banger of a unit that has performed extremely well over the years. Now... would I buy the Turbo? Not exactly. I would build the most insane machine with my years of CNC experience. But that machine would have to retail for a price that would be out of the range for most customers. That's the reality of running a business. Either way, this was an orchestrated attempt by the competitor to rather than come up with a better machine, just tell everyone how bad the alternative was.
