[handlewanker]

Hi, It's so degrading to hear anyone refer to someone's effort as mere hobby engineering, whereas they will probably be using the device whatever to make real money, even modestly.........Wilbur and Orville were bike mechanics before they went to flying.

The subject of ball screws is a deep one, as most if not 99.9% of us would not be able to determine the difference between a rolled ball screw and a ground one apart from the appearance of the trackways.

Rolled screws ARE DEFINATELY HARDENED.....well mine are.....make no error on that part.....attempting to run a hardened ball on a soft surface will immediately cause the balls to dent the surface and so you have no ball screw.

The difference is it is cheaper to roll a track in a steel bar, and harden it than it is to roll one, harden it and finish grind it, one reason why it cost more.

I would hazard a guess (complete ignorance on the methodology for production here) that precision ground screws start off by being rolled then hardened and then ground to fine limits, whereas the rolled screws just rely on the accuracy of the rolling medium to produce the pitch over a specific length.

This is similar to screw cutting in the lathe.......just cutting a screw and hardening it leaves you with the accuracy of the cut thread and tolerances that are affected by the hardening process.........that is the first cost outlay.

If you went to a further stage and had the screw ground it would add at least the same amount again to the final product cost.

Provided the rolled screws have hardened tracks of sufficient hardness to last, then the fact that they have some backlash is irrelevant as backlash can be eliminated by fitting two ball nuts etc etc as I mentioned before, and so making a mongrel into a thoroughbred.

The big difference in quality would ultimately be the hardness of the ball track, irrespective if it is rolled or ground, as if the track is not all that hard it WILL wear out quicker or have backlash sooner.

What point would it be to have a cheap rolled screw with a softer track when a hard longer lasting track costs no more to produce.

Case hardening is case hardening and the quality of the case is purely a product of how long the bar is kept in the cyanide bathe or whatever it is case hardened with, but the big problem is controlling the tolerances for pitch and straightness of the bar after the hardening and quenching process........I hazard a guess that the hardening process is done with induction hardening as this can be done along the threaded bar progressively.

In that case, the bar is not case hardened by a case producing chemical additive process, but rather formed from a metal with high carbon material which only gets the top layer hardened by the induction and rapid quenching process, similar to the production of carbon steel band saw blades that are produced on a continuous roll and get the teeth hardened just at the tips.

I marvel at the ability of the manufacturers to produce the balls screws at such a low price.

Anyone who has lathe experience and can cut threads can cut a ball screw track on a piece of steel bar, but the crunch comes when it gets hardened and goes out of wack from the expansion and contraction making any pitch accuracy non existent......we can't even imagine that the bar will remain straight when it gets hardened and then quenched.

I have a rolled ball screw and nut with a second nut I bought to do the double ball nut experiment I mentioned, and when I have time I'll do the double ball nut exercise to prove that it is feasible and totally practical to have cheap ball screws that are backlash free.
Ian.

[jerrybell]

double ballnuts are nothing new but if you think they don't wear out you have a lot to learn.

[handlewanker]

LOL.....

[jerrybell]

LOL...

[uberlinuxgeek]

Well my new bearing items are here and fast from the eBay auction. But here it is now I see why people stop participating and I am there. I will no longer be as well. Thank you for the constructive comments. Damage done for those that not. For those that do see you elsewhere in other sites.

[handlewanker]

Whatever.......good luck.

[BlackICE1]

Well my new bearing items are here and fast from the eBay auction. But here it is now I see why people stop participating and I am there. I will no longer be as well. Thank you for the constructive comments. Damage done for those that not. For those that do see you elsewhere in other sites.

I hope you can see past those non-constructive post and come back and post your results. I'm curious to what you discover.

[gio666]

X Zero,
If you are hoping to get people to look at your product, just buy some advertising space. Your negative comments combined with atrocious spelling and grammar are doing you no justice.

I have know idea at all what negative comment I gave . I deal in ballscrews everyday, I have seen lots of ballscrews and know the difference, I see more ballscrews in one day then you will in your life.
I have gone through all the same stuff and lost lots of money on same stuff people are talking about now .

Thomson and word cheap are 2 things that don't go together. If there is Thomson for $20 a foot and ballnut for $30 . I would getting them myself. But they are not Thomson and they are also a lot of money for larger ones.

I don't think telling people to buy better ballscrews and not the cheapest ones on ebay is going to help me with advertising when I don't sell ballscrews? I don't sell metal working machines.
But good thing for me I don't need to advertise. I guess grammar I will have to work on for you , almost forgot XZero CNC Routers

[smallblock]

Well, since this thread is about a nut with some balls missing, we should respect your expertise.

[gio666]

Well, since this thread is about a nut with some balls missing, we should respect your expertise.

I have done what people are doing here when I first started. I tried changing balls in ballnut with NSK and made no difference. I have had ballnut that drag in a spot every turn. Nothing will fix that.
I have had lots of ballscrews before that only had half the bearings in them. I have tried using larger balls in ballnut ,only to have it lock up and have to take hammer and hit ballnut to make bearing explode.
Some ballnuts half empty, loaded more bearings to have ballnut drag every where. SO half the bearings make it run better.
Tried using 2 ballnuts, no change. caused a lot of drag making motor stall easy.
Trying to save money ended up costing twice as much , just buy better .
People don't need to listen , welcome to try things yourself .

[Fiero Addiction]

I have know idea at all what negative comment I gave . I deal in ballscrews everyday, I have seen lots of ballscrews and know the difference, I see more ballscrews in one day then you will in your life.

I'm can't pinpoint the exact reason why, but you come across as an *******. I'm sure you're a really nice guy in person.

Thomson and word cheap are 2 things that don't go together. If there is Thomson for $20 a foot and ballnut for $30 . I would getting them myself. But they are not Thomson and they are also a lot of money for larger ones.

I don't think anyone would be surprised that larger screws cost more, certainly not an expert like yourself. The example I gave was for the 5/8" screws because that's what was used on the Shopmaster machines and this is the Shopmaster forum. I could search out the posts where people have ordered those parts from McMaster and received Thomson screws, but at this point it would be a waste of my time. In less than a minute on Google and I found similar prices from other sources.
Thomson ball nut $48.60
Thomson ball screw $18/foot

[handlewanker]

Hi Gio, I wouldn't worry too much at people who want to rub you up the wrong way just to be antagonistic, we can all profit from your expertise and I think we're all adult enough to know when someone is plugging a product even if we subsequently look at that product and go for it.

There's a lot of technicalities that wash over the average users head if'n they don't realise the potential for buying good once as opposed to having bad all the time.....bad never gets better ever.......while good will mellow with age and last longer.....my 2 cents worth, I don't always practice what I preach.....but $18 a foot has to be good yakka by anyone's judgement.
Ian.

[BlackICE1]

Has anyone upgraded the screws and ball nut on the Patriot? How difficult is that?

[gio666]

Hi Gio, I wouldn't worry too much at people who want to rub you up the wrong way just to be antagonistic, we can all profit from your expertise and I think we're all adult enough to know when someone is plugging a product even if we subsequently look at that product and go for it.

There's a lot of technicalities that wash over the average users head if'n they don't realise the potential for buying good once as opposed to having bad all the time.....bad never gets better ever.......while good will mellow with age and last longer.....my 2 cents worth, I don't always practice what I preach.....but $18 a foot has to be good yakka by anyone's judgement.
Ian.

Thanks Ian , I'm not worried about what anyone says.
Actually $18 a foot is very expensive for what you are getting. Accuracy is .004' . that's 4 thou accuracy just the screw itself. In terms of precision ballscrew that is horrible. Those are more of a precision rolled thread rod than precision ballscrew
Those ballnuts in link are designed to use in their actuators and some only 3 rows of bearing. If you look at tech info, it does not support much load Surprised someone would use for steel cutting machine . For steel machine you need double ballnut and at least a flange ballnut.

[countryguy]

Hi everyone- To stay on point w/ this thread - It's a LOT of trial and error with these hobby mills. Backlash in 2 to 5 even upwards of 8 to 10 thou.... I think maybe anticipated I suppose. To get it down to .001/002 repeatable for me meant I was happy. You're not going to get to 4 places on these w/ the Z as is and such... IMO. So I've set my expectations. I tried to tighten, clean, inspect, etc and upon changing the balls on mine- I did get much tighter results.

there is a great article here on Rolled -vs- Ground screws. Precision Ballscrew Threads: Rolled versus Ground We've have not mentioned those at this point I do not think.

The point about balls w/ alternating various sizes to offer consistent performance made a lot of sense! So to the other points about binding and locking- You bet. So it's balance, and trial and error on how your setup runs. These mills do not have wipers or screw covers. I know mine had a lot of debris in them before I replaced the balls. I do plan to cover these up better. Since we're cutting 1045 and the .375 end mill cutter depths and widths are very low (it's a small mill remember) I get 'micro-swarf' via carbide and I do run Mist.... So this swarf gets into everything. Not too happy for the screw setups I'm sure!

It's fun to tinker w/ the Mill. Fun to make it better and as a result of trial and error- the success even more appreciated (to me anyway). With the Mill prices the way there are in the midwest I elected to keep a hobby mill as just that. And I purchased a 30 taper CNC mill w/ really large precision ground screws and a large table and VERY heavy frame. And for 1/2 the price of a new hobby mill from most of the players in this market. but I still LOVE that hobby Mill.... for what it is though.

I know I'm here to learn and I hope present some of my experiences good and bad. Of course YMMV (your mileage may vary) and so the myriad of comments on various attempts. All worthwhile and valued. Lets simply choose to move past text that may seem too passionate or even out of place. Just take it like it's your Bro/Pal.... And smile , nod and move on. Deal?

[smallblock]

. These mills do not have wipers or screw covers.

Countryguy- good post. This whole thing sort of drifted off topic. However, the Shoptask / Shopmaster machines all came with good lead screw covers and bed wipers since back in the 90's. Not sure if you bought a used machine with some parts missing or--

[countryguy]

Thanks SB. Yeah, you are right. being new, I guess I meant the ball screw round sleeves I see on some higher end Mills. The Wipers are there on the dovetail for X. And yep- The screws are essentially covered up... But I still seem to get chips and debris everywhere at times. Now I just make sure I blow off the screws. My unit is a 2010 w/ the X screw on the outside edge. Besides needing a larger screw, (imho) it's in need of a better cover somwhat. I'll get a break to someday and cover the inside exposure. :-)
thanks for the post. Yes, the Wool wipers are a nice touch... On my Y saddle there are no wipers. Hmmmm I did not even consider them here.

So what should I/we be using for screw lubrication? Oil collects dust and swarf. WD40 seems OK by me? What is there for us Hobby folk?

Countryguy- good post. This whole thing sort of drifted off topic. However, the Shoptask / Shopmaster machines all came with good lead screw covers and bed wipers since back in the 90's. Not sure if you bought a used machine with some parts missing or--

[victorofga]

If one looking for the basics of ballbearings then find answer..

by its geometry ballbearings can not be backlash free..
on the first picture I try to show it.. because the different point on the ball try to take different distances..

another point when ballscrew wear, that will wear not as a ""larger radius""

but wear will be something ellipsoid..

and for last, these machines cant afford high quality ground ballscrews.. and honesty theres no reason for them really..
if we count on what the control can perform, and what tool available in a general small shop for measuring.. then 0.01 mm the limit..

and this was the reason I tried to suggest simply replacing it ... to get backlash to 0.01 mm already need a new ball screw and two nut tighted against each other..

ballscrews due the expectations of precision, shouldn't be without covers..

and again affordability, the rolled ballscrews for that.. all need is replace frequently them.. and you can keep backlash around 0.015 mm

================================================== ====================

imagine if you try to put larger ball into the way, how it could eliminate the backlash? you cant put into an ellipsoid ball :-)
gio just give same explanation.. when he said some nut filled only halfway..

[Fiero Addiction]

Victor, The Nook and Thomson screws that were used on these machines have a gothic arch profile, so that doesn't apply to those. I'm not sure about the newer machines.

CG, I wouldn't use wd40 to lubricate any bearing.

[sharpshooter90]

I think the original point got lost early on when one poster assumed that the screws were worn. I doubt that wear is the issue on a hobby machine - it's more likely just undersized balls from the factory, or possibly balls missing during the assembly process.
Country Guy- stay away from WD 40- it eventually dries to a sticky gunk.