Thread: Bridgeport lead screws in Aus

Have you thought about going ballscrews and nuts straight out of China?
Pretty sure you could get the both X and Y with whatever end machining done for well under $500 posted to you.
I remember some years back seeing the larger manual Mills from Hare and Forbes having ballscrews from factory, probably still do.

Originally Posted by Dave J

Have you thought about going ballscrews and nuts straight out of China?
Pretty sure you could get the both X and Y with whatever end machining done for well under $500 posted to you.
I remember some years back seeing the larger manual Mills from Hare and Forbes having ballscrews from factory, probably still do.

I would be interested at that price. Do you have any suggestions? Any idea of the quality of these units?

Thanks for your help.

[QUOTE=Hunch;1950942]Just by coincidence, have got to send some spur gear drawings to a supplier in China, he has bugged me again

Thanks Hunch

I am investigating Sino options tonight.

I and thousands of others on CNC zone etc have bought from linearmotionbearings on eBay, he is great to deal with.
Google him as it doesn't usually show up on Australian ebay.

Linearmotionbearings2008 has only got up to 25mm which I think would be fine be as they are hardened, all the guys I've seen converting Bridgeport Mills use 25mm.

If you want go 30mm, you need to go up to 32mm, look up 159app on eBay as my pictures aren't loading tonight for some reason.
The 32mm ones and still very reasonably priced and you will only need a single nut for a manual machine, even CNC guys only us one nut sometimes.

At a guess of your sizes it's $320 for a 1250mm one and $144 for a 400mm one, both including postage and including end machining, might be a little more for custom end machining.

I was wrong, I just googled linearmotionbearings and he now carries them, he never used to.
The 1000mm one I quickly found with one ballnut is $177 posted.
Message him with your length and ask about custom end machining. You may get out of it for around $300 for both as he combines postage.

I was looking at buying a 32mm one for my knee and was going with the 159app guy, but learnt something tonight so will buy through linearmotionbearings.

Just a word of caution about replacing an Acme leadscrew with a ball screw. Ball screws have so little friction inherent in there design that without restraint {which is given with a servo motor on a CNC machine} such as when feeding manually , the screw can be driven in reverse by the cutting action with rather disconcerting results.

I had a Stanko toolroom mill which had a ballscrew on the Z axis. There was a one-way roller clutch connected to a disc brake which held the table from dropping down from its own weight. The little spring which actuated the roller clutch became jammed and the table took off downwards at a great rate of knots. With the spring replaced , modified, all was well again.

I doubt whether a Bridgeport would have restraining devices on the leadscrews so perhaps a bit of further investigation is required. There will no doubt be blokes who have converted Acme screwed machines to ball screws and I would be interested to find out what is required to do it safely.

I had a bit of a read on practical machinist after posting this, a lot suggested as long as the thread pitch was similar they would be fine.
My machine is 3.8mm a turn of the hand wheel (something stupid from memory) the standard ballscrews are 5mm, or 10mm.
Having thrust bearings on one end tightened up a little or similar would help as well.

Originally Posted by Onslo_tas

Thanks Charles, that is very useful information. Your experiences haven't been fantastic. I think I might check back with you as to how this latest lot goes. I am less keen after hearing about the repackaging into cardboard.

My fault, Onslo, not fully explaining. These 'forwarding' companies have a basic service where they send you the package as received from your vendor and in my case they have been strong enough. The other service they offer (for a little more $$) is to re-package to a single carton when you order from multiple vendors and that was where my losses occurred. The cartons they supplied and the internal packaging weren't anywhere near strong enough.

Thanks for all the info and help everyone.

DaveJ, I tried linearmotions eBay site but he seems to not list them so I have messaged him.
I expect I will need to furnish him with drawings but I cannot track them down anywhere. My machine has the electronic power feeds on both axis so the shaft ends are likely different to hand wheel only ends. I have a missing Longitudinal screw so no sample to measure up even.

Are folk using right hand threads in both axis. Reversed Y axis might be a pain for a manual mill, probably no problem for CNC

Any good links for where these ball screws have been used?

I found a drawing and a good info page on using the standard Bridgeport yoke with 25mm ballscrews.
https://www.cnczone.com/forums/bridg...00304-cad.html

This video popped up in my youtube feed the other day, i haven't watched it but it may be applicable to installing ballscrews.
https://www.youtube.com/watch?v=Dt4f-FGwx_0

They mention there yokes in the thread I linked

it might be worth talking to Hare and Forbes (aka machinery house) about screws and nuts for their bridgeport clone machines. I have an old clone (herless from the early 1980's) and the parts in that are identical to the bridgeport drawings and threads.
H&F might be able to supply the parts you need at a decent price

Des

Originally Posted by Onslo_tas

I have a series 1 Bridgeport that needs new nuts and lead screws. Originally a metric machine I may convert it to imperial given the price difference for metric screws and nuts (Divisions mean nothing with DROs).

The problem is that freight from the US or UK is very near the price of the screws. Probably the screws length contributes to this as some suppliers cannot ship long packages to Aus.

My question is are there ways around this? Alternative freighters, Australian suppliers (I cannot find one). Anyone converting a BP to ballscrews for CNC conversion want to sell me serviceable screws and nuts. I would prefer to keep it metric but it is not worth $800 more.

Thanks to all for the suggestions (I was going to say leads). I can get freight for new screws down to US $380, better but still a lot. Before pulling the trigger I am checking out ballscrews from the link to Hiwin, thanks for that.

One problem is finding the different drawings for the power feed ends. I might have to do that myself. Hiwin have drawings for hand wheels only. Failing that I can get extra long screws and have them machined here. My little Emco is too small in the spindle unfortunately.

Hopefully I can have something underway this week.