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I have three new ballscrews to sell:2 of RM1610-780mm, 2 ballnut, end machining(F=25mm)1 of RM1610-660mm, 1 ballnut, end machining(F=25mm)They are end-machined in the normal fashion except the cylindrical portion has been made longer, 25mm, to accommodate fixing pulleys more easily.Will sell individually or as a lot, don't really care. Can cut to length and end machine if required.
Attachment 5447
Will consider all offers...also interested in exchanges for something good, like profile rails...
Shit Jonathan I've just ordered 2x800mm from Chai and these would have done the job. .!!!!!!!!!!!!!!! I'll see if he's sent them yet.
Did they come machined or did you do it.?
Chai did it, why do you ask just out of interest?Quote:
Originally Posted by JAZZCNC
Because you shit on a lathe.. . .:rofl:. . . . . . .No Sorry actually would have been better to ask if you machined them to match the BK/BF blocks that's what I was asking for really.Quote:
Originally Posted by Jonathan
With them having 25mm shaft then I wondered if you had done them for a special reason and none standard bearing block or self made design. No slur on your machineing prowess and would or will happly bought/buy them if you had machined them to match BK/BF blocks.
Edit: I've just emailed Chai to see if orders been sent or too late to cancel the screws so may be intouch.!
No, easier pulley alignment is the only reason so they'll fit BK/BF blocks. I wouldn't be caught dead with a BK/BF block anyway.
Jonathan just PM'd you
Nah now't wrong with them they just need a little TLC some times thats all, certainly can't make them any cheaper.! . . . Anyway I'll be using FK/FF blocks.!!Quote:
Originally Posted by Jonathan
Come on Jonathan are you holding out for Jazz to snap them up? :naughty:
Nope he's waiting for my higher bid.!!!Quote:
Originally Posted by 2e0poz
ha! ha! ha!
Think he is hoping for a fortune then?
Ok I'll declaire my self out the race go for it Epoz.!!
This is why I lke dealing with the Chia, he must not sleep.!! . . It's 6.19am in China I emailed him 45 mins or so ago and already got a reply. .:clap:
Much as I'd love a higher bid, if Jazz cancelled his order and I sold the screws to 2e0poz, then that would have been a bit harsh on Jazz so I thought I'd wait.
FK/FF blocks are the easiest to make as all the accurate bits are on the lathe. How much do you pay for them, lets see if I can't do them cheaper :naughty:
LOL! no worries i knew this was the case just could not resist :lmao:
Jonathan out of interest why are you not using these on your milling machine? You said you were going to upgrade it at some point?
If they were 16 x 5 nobody would have got a look in, 10mm pitch is too much for what I use these for.
Go for it.!!. . . Just payed 60 dollars for 4 so thats £38 or £9.50 each. Plus a bit of shipping but thats mixed in with everything else I've ordered.Quote:
Originally Posted by Jonathan
Ballscrews are still for sale.
Same reason that John S hasn't bought them - 10mm pitch is suboptimal for the milling machine or lathe.Quote:
Originally Posted by 2e0poz
They were going to be used on a machine I'll soon be making, but due to design changes they're no longer suitable so I'll be buying longer ones.
How much does the shipping work out at if you calculate it proportionately by price? Assuming that's £9.50+shipping per pair of supports then it's not going to save much. I'll still make my own as it's so much less restrictive and guaranteed not to have dodgy bearings or the wrong fit on the bearings.Quote:
Originally Posted by JAZZCNC
Sold, now to get some more.
Jonathan my screws have just arrived from Chai.!!!. . . . .WRONG. . . . sent 5mm pitch not 10mm so may become available depending on what he intends to do about it.?Quote:
Originally Posted by Jonathan
Knowing Chai we'll come to some deal, I need 10mm pitch so they will be available or going back thats for sure! . . .. . I'll let you know what happens.!!!
7 days from ordering - not bad at all.
I'll be interested in at least a couple of the 5mm you end up keeping them.
Just out of curiosity, is there a rule-of-thumb for whether and when to use 5mm or 10mm pitch ballscrew when constructing an XYZ table (for routing mainly hardwoods)?
It depends on numerous factors. 10mm pitch gets you much better speed and acceleration, but unless you use pulleys (which you really should...) you clearly have half the resolution of a 5mm pitch screw. If the axis is quite long you'll certainly want a 10mm pitch screw, since because the screw pitch is greater the rpm for a given feedrate is less so the screw will not whip until twice the feedrate it would with 5mm pitch. For a short axis, like Z, whipping isn't a problem so 5mm is fine. In most cases on a 'reasonable size' router 10mm pitch with pulleys is the way to go for X and Y and choose the pulley ratio depending on what your're cutting (to favour resolution for speed).Quote:
Originally Posted by Karl
However clearly there will always be exceptions and each case is different, so you need to read up on it, decide and calculate for yourself.
Not if the bastards are wrong.!!!!!!!!!!!Quote:
Originally Posted by Jonathan
Jonathan the screws are correct and I owe a big apology to Chai. . . . Just spotted it's twin start thread.
In my defence it's the first time he's sent me twin startscrew:redface:. . . . Better send him an email quick. .:whistling:
Hope the ball nuts are double start as well:heehee:
Peter
Has Chai given you any load ratings or datasheet for these twin start screws? Would be interesting to see how they compare to the single start. Do the ball-nuts have two or four rows of balls and are they the same dimensions as the single start nuts?
Spot the difference.!!! . . . . Can You see know how I didn't spot It was 10mm pitch straight away.!! . . .The nut length gave it away.Quote:
Originally Posted by Jonathan
3 circuits (rows) 6 plugs. 3 circuits is a typical for 16mm dia, 4X usually on 20mm and above.!
As you can see quite a bit longer body and obviously ever so slightly more resistance due to extra set of balls.
No didn't get any Datasheet, I didn't even know he was sending me twin start so didn't ask. I will email him to see if he as any specs.
Will be a couple of weeks before I have them on the machines and working so will let you know how they perform.?????
So what's the rationale for using pulleys to drive a ballscrew rather than connecting the stepper motor directly inline via a flexible coupling?Quote:
Originally Posted by Jonathan
Couple reasons really.Quote:
Originally Posted by Karl
Easy to gear for extra speed or resolution/torque. It also helps reduce resonance that affects the motors.
Many thanks - I hadn't considered the potential flexibility offered by interchangeable gearing.Quote:
Originally Posted by JAZZCNC
That raises the question: What brand/source of pulleys/belts are currently in fashion/recommended?
{Presumably, belt manufacturers/suppliers provide tensioning guidance?}
Thanks
Karl
I always use HTD 5mm pitch 15mm width and a good brand is Gates, medway etc. If you go to any good bearing supplier and tell them you want quality brand not the cheap veriety they should be able to help.Quote:
Originally Posted by Karl
Many thanks. Are more pulley teeth better than less? Eg for a gearing ratio of, say, 1:2 is there anything to be gained from using 12:24 teeth pulleys as opposed to 20:40 teeth?Quote:
Originally Posted by JAZZCNC
Karl
Yes it's all about teeth in mesh.!! With small pulleys there are less teeth engaged between belt and pulley, less teeth engaged means less able to handle high loads and reduce the amount of torque that can be transmitted and if wrong will rip teeth off the belt.
Read these and it will explain lots. . http://www.roymech.co.uk/Useful_Tables/Drive/Timing_belts.html
http://www.ondrives.com/data/pdf/pul...belts-tech.pdf
Jazz did you hear anything from Chai?
With 6 plastic inserts they must have 6 rows of balls, as each insert is a ball return tube. Additionally they're not going to use 3, or any odd number, rows of balls as that would result in uneven wear and all sorts due to having more balls running in one track...
I wonder if they're preloaded. A twin start screw with offset tracks in the nut is one way to apply preload - that would make them worthwhile.
As a general rule of thumb don't go below a 15T pulley with 5M HTD belts, and if you need much above 3:1 use double reduction. Use one of the many on-line calculators to find the number of teeth in mesh on the smallest pulley. They will give a warning if it is below 5...
http://www.sdp-si.com/cd/default.htm
No not heard anything yet but I only sent email late last night so don't expect too.Quote:
Originally Posted by Jonathan
It's a flop over type nut so Yes it's 6 rows but 2 x 3 circuits per start. Like this http://motionsystemdesign.com/images...-ballscrew.jpg
Well thats how believe they are setup but I'm not striping it down to findout.:lol:
Yes by the feel of it I do feel that it's slightly preloaded as well.??
Hi Jonathon,
Are these still available.
Dean
They've sold to Jazz, sorry.
And he has the nerve to bad mouth you ?
I'd have scrapped them first................
Now there's an idea ... we've not actually managed to get them posted yet! Parcels2go failed to collect twice so going to try again on Monday.Quote:
Originally Posted by John S
John I'm a professional.?? . . . I never mix business with pleasure. .:hysterical:Quote:
Originally Posted by John S