Another which is better R&P,Ground ballscrew,rolled ballscrew,Acme,beltdrive etc.thre
Which is better? How about what does each type cost vs performance.
We all want low cost/greatest accuracy.If you know pricing,please share info.
I will start with pricing I know.Lets compare the different actuators based on 8to
From McMastercarr Nook ballscrews,rolled I beleive.
100"$272 Angular bearing block $ 366 ,Unsported side $100 nut $80 Total $818.00
THK rolled 2500mm, Dia 25mm/5mm lead $217,nut $130,angular bearing block $359 unsupported block 105, total $ 811.
Americans or Canadians can buy THK direct. WWW.tos-world.com
Belt drive.Off the top of my head 25mm belt,12 bucks a foot X 20' $240+2pulleys approx $60 total $300.
Have never found pricing on THK ground screws.Really don't want to know.Anybody Know?
R&P Idon't know much.Anybody have pricing?
Look at the specifications....look and the prices.....and then consider your requirements.....do the math....let us know what you find.
I think a decent quality rolled ballscrew (nook, rockford, roton), with homemade end bearing blocks won't cost much more than a belt-drive/R&P system and would be more accurate.
I thought pricing on various linear motion stuff would be interesting.Apparently not.Come on guys post some links and or pricing on rolled balscrews,ground ballscrews,acme etc..Are we too lazy to bother?I did my 2 cents worth.Can someone else add?or do you want me to find more?
If no one knows anything about linear motion pricing,maybe we should discuss which is the best beer.My vote is a German beer,Holsten Festbock.What is your favorite??
The price thing is interesting. The spread between THK & Hiwin Linear bearings is amazing. The countries of origin is the reason.
Watching Ebay is very interesting also. There is a very robust market for linear anything! Small scale CNC is growing.
after a lot off surfing the www.......com about this product i found that rolled is good enough for a lot off the hobby machines build here on this forum. Remember when using a 0,008 mm precise No backlash screw with hyper support bearings you need to build a frame that is dead-on precise to. And that costs MONEY.
Look at the application:
If you are milling a lot off alu. and often some mild steel and aren`t in a hurry like a production machine, i think rolled screws are fine. get some nice bearingunits and focus on the frame and aligning. If money isn`t a problem buy ground ones and make the perfect machine like a Fadal or Haas.
Bellow some nice products with prices, a lot off the products are from hiwin, looks nice just like THK etc...
The most important is to calculate all the forces in the machine when milling you`re part. multiply it with 2 and compare with the ballscrew sheets.
If you pay some more you get the no backlash ones, otherweise you get MAX.0,05mm backlash.
If you are making parts that go into space this above doesn`t work.
Look at the dealer in you`re own country, prices will be about the same.
How much do you want to spend????
The retail cost of a drive system involves simple research in to the respective system that you're looking to buy. Unless you can find a price sheet for the respective system, you're in a sellers market. Sometimes there are "deals" available and sometimes you get screwed by having to buy at retail. Yesterdays "deal price" is only important if it is still available today - otherwise, it is only something that will make you laugh or cry otherwise.
Ebay pricing is hit miss and heavily luck reliant. If you have the money and it fits your need BUY IT. Otherwise, dream on and save your pennies because it will probably be gone when you come back to it when you realize that the deal was too good to pass up, and did.....
As far as accuracy goes, Viper's reply in post #2 pretty much says it all. After having made any number of recommendations, I've gotten the "but I really don't need that loeel of cost/accuracy so why should I buy the ground ball screw????" line more often than I want to ever hear.
The fact remains, a ground ball screw with super precise ball screw bearings is pretty much THE most accurate positioning method used on pretty much ANY high end machine - period.
Everything else is a lower performance compromise that is adequate for the performance requirement dictated by the user or creator of the equipment fitted with the compromised drive or the available budget.
The following posts may be of assistance:
Ball screw basics:
http://www.cnczone.com/forums/showthread.php?t=20748 (Ball Screws 101)
Ball screw treatise, the hard core stuff:
http://www.cnczone.com/forums/showth...?t=8813&page=1 (Ballscrew Basics)
Ball screw backlash:
http://www.cnczone.com/forums/showth...t=18178&page=9 (Vince's BP CNC conversion) (lots of detail here)
http://www.cnczone.com/forums/showthread.php?t=25181 (Eliminating Backlash 101)
No matter how you cut it (no pun intended) or how the question gets asked, the answers and compromises pretty much remain the same.
And the answers are usually preceeded by the "how much do you want to spend????" inquiry.
Excellent response as usual.The drift of the thread was mainly to compare pricing of various linear actuators.I still don't know what ground screws cost.There appears to be no pricing on line.
From reading your responses I became a convert to ballscrews even for woodworking.Being "In the Business"sanding to tolerence to "fit" is time consuming and depends on worker skill.Time is money,sloppy fit causes rejects,weak joints,fill& sand,fill& sand etc.What I am trying to determine is
HOW MUCH IS A 10ft.ballscrew?When I find the cost differences I can justify the added expence based onthe time saving.BTW please look at General mechanical/engineering design polymer concrete.I think you may have some knowledge/advice on the subject,which may be helpful to ZONERS.
BTW I am not lazy,I have done tons of research on pricing,but it appears ground ballscrew pricing is a trade seckret.
The reason why not so much is published on ground screw pricing is that most ground screws are "made to print". Unless you buy a stock item (ala one for a Bridgeport mill), you're probably going to have to have it custom made - especially one that is 10 ft long.
I'd be inclined to call HIWIN. Don't bother e-mailing. They'll want to see a drawing so check out their on-line catalog for ideas and at least have a bar napkin sketch available (preferably something a bit more professional) for them to respond to a RFQ for.
You'll also probably need anticipated axial loads, HP curve of motor, screw pitch and speed that you hope to move at.
Re: polymer concrete - this topic was discussed rather well in a thread where a guy wanted to fill his mill with the stuff in order to increase stiffness. Whatever was said (by me and others) in that thread, surely, still applies. A site search via the search engine should turn up the thread without too much trouble.
My machine is 3m by 1.75m , belt driven for both X & Y axis, so take a look to the following post may be of assistance:
http://www.cnczone.com/forums/showthread.php?t=29390 (Choosing a drive screw and motor for a long axis?)
As to rolled screws, they are not all equal, and the same for ACME, both have higher precision ones avail. Standard rolled nook is .003 per foot as I recall, but they make a rolled .001 per foot variety too for more $, I know because I bought a 3/4 one 6' long from IH in their going out of business sale :-).