Emco FB2

Hi all has anyone with an emco fb2 mill had any problems with the standard soft cast alloy leadscrew nuts ? We have 3 fb2's and they all suffered from excessive play, and when adjusted at the worst wear point to acceptable backlash tolerence, the leadscrew then became too tight in other less worn areas. we renewed the leadscrews and nuts 3 years ago with genuine parts from pro mach, but now the machines all show signs of excessive wear backlash. I was suprised and disappointed when we pulled these machines apart, to find that these nuts were made from a very soft die cast alloy. Even the cheaply made chinese stuff have phos bronze leadscrew nuts as do all quality made machines such as myford, bridgeport, colchester etc. Well as I have a full cnc workshop i have now created a ( metric)phosphor bronze leadscrew nut for the fb2.initially Machining them from 2 1/2" round bar (gauged) screw cutting the trapezoidal thread, then finishing off all milling operations on my 5 axis haas vm. To produce an exact but far superior version of the emco nut, This wasn't a cheap option, but then the soft original alloy nuts are £50 each.and now fitted with new leadscrews from pro mach our 3 fb2's are transformed and will give years of backlash free service. If anyone is interested I made an extra 10 of these nuts whilst my machines were set up cheers kev

Kev;

Well done.

On "http://bbs.homeshopmachinist.net" there are threads on "acetal" plastic nuts made to fit existing screws.

Very impresive work, even by one of our moderators on this forum.

I have not made any myself, but they do look like a very interesting way to proceed.

Another JohnS.

As I read your mail I suppose the nuts are not the problem but the leadscrews. They wear on the most used position and create backlash. When you try to correct this the nut jams on the less used position creating more wear on the nuts. You can only correct the wear on the nuts ( at the less used position ) and NOT the wear on the leadscrew. Replacing the nuts only is of no use. To cure the problem you have to replace the leadscrew too.

Kind regards,

Johan.

Edited By Johan van Zanten on 01/06/2013 19:17:10

Hi johan the problem IS created by the use of the the aluminium nut as this creates an electolytic reaction between the two dissimilar metals. The steel leadscrews are fine once used with phosphour bronze nuts. We have proved this with our combination over the last 7 months, our 3 x fb2 machines are used 5 days a week, for approximately 5 hours per day , in our R&D dept by students, we have the standard emco leadscrews and with the phos bronze there is no sign of the usual wear inherent to the fb2

Had a similar problem with an old Myford belonging to a friend, it had excessive play in the cross slide, we thought worn nut. On stripping down we found it was the lead screw was very warn, and the nut looked OK, we went to the one time Myford agents in Christchurch, and one of the older staff members found a brand new one hidden away in the stores dept, we got it for the marked price, 5 Pounds NZ, $NZ 10, that was about 15 years ago. I consider that it is grit getting embedded in the soft metal of the nut. The nut was not bronze, it looked like an aluminium alloy. Ian S C

Hi Ian thanks for that, very unusual indeed for a myford to have an aluminium leadscrew nut, how old was that machine ? Did the nut look home made. We have 2 x 254 lathes one imperial (1986)one metric (1994) . The leadscrewson these are phos bronze even the one in the tailstock, we make phos bronze leadscrew nuts for a local firm who repair four post car & trick garage lifts, they are exactly the same set up but much much larger and extremely expensive ! Emco used die cast alloy simply to keep the cost down, which unfortunately was the achilles heel of the otherwise perfect little mill. If i can figure out how to do it i will upload some pictures of the nuts we made for the fb2 cheers kev

hi all...if anyone is interested I will post the spare leadscrew nuts I made on fleabay within the next 2 weeks... I have 8 spare (metric) ..(4 pairs).. I don't anticipate making anymore as they were rather time consuming & the material costs wase £335 ( just enough to make 14 leadscrew nuts).. I have used 6 myself, They Are A VAST improvement on the cheap HE30 ally ones now made by emco..If I had made them from the same material as Emco The Material cost for HE30 would have been £60 to make 14. So why Emco charge so much for theirs is a mystery Regards..Kev

When I made a new cross slide screw for my small TOS lathe about a year ago I also made a new nut out of PB.

The original one was out of PB and did about 14 years in daily use in a jobbing shop and not nursed in any way so I thought that was good enough.

the nut is a nice design and adjustable for backlash, that much so when it finally gave up the ghost it had hardly any thread in it but also hardly any backlash. Screw wear was the worst culprit at this stage in it's life

I have done nothing to change the design but when i had finished the screw, tried it and was happy with it I sent it for Tuftriding, this is a low temperature [ 400 degrees C ~ ] hardening process that puts just a few microns of hard case onto a surface but most important it does not change dimensionally or warp.

I'm confident that if the original lasted 14 years from new this one is good for at least 20.

Yes Phos Bronze Is The Way Forward With The FB2's I Agree It Is The Best Material to use on this application,We Use Phos Bronze For The Car & Truck Four Poster Lifts We Machine Phos Bronze Nuts These are in daily use and have to endure far more pressure than any milling machine or lathe ever will.

The FB2 Nuts Are Made From HE30 Not Mazak, We Have bought them from Pro Mach, And We Have Their Old Die Cast Version And Their New "solid" version here. It seems Cost Comes Before Quality.

I now have 3 FB2's all fitted with 3 Axis Newall DRO's & Newton Tesla Variable Speed Controllers, Which Use 240v 3 Phase motors,

Cheers All..

I have two FB 2's. One has given no trouble over several years of use in building a loco. The other came with enormous backlash on the y-axis. After several fruitless attempts to sort the problem by tightening the nut, I took the slide off and discovered that the nut was loose. I tightened the securing bolts, re-assembled and have had not trouble since with virtually no backlash. Whether this situation will last over future years of use remains to be seen. I hope so as the cost of replacements is eyewatering !

Mike.

Hi All, we have today been contacted by an Austrian company asking if we can supply the Metric Leadscrews in an Induction Or Case Hardened Material. To Go With The Nuts we have already made for the FB2. They Have provisionally ordered 30 Sets (60 leadscrews & nuts). Would anyone like to tag on to this order? Contact Me for Full Spec / Pricing..Thanks...Kev

PS: obviously all of these will be (gauged) screw cut in their metric form.On Our Haas CNC Lathe (Nut & Leadscrew). Not Tapped as some cheaper varieties & Emco Originals

Hi All...Thanks For The Numerous E Mail / Messages On here...Here Is A Picky Of Our Phos Bronze Leadscrew Nuts, Alongside The Soft Cast Ally Emco Original. Our Version Is Within 0.05mm Of original. We Machined Them From Round (CNC Haas), Screw Cutting The Metric TP20 x 3 Thread, "Gauged". Then Finished Them Off On Our 4 axis CNC Haas VM2. I Have ordered The Material To Make The Leadscrews To Match, When Finished These will be Induction Hardened. They Won't Be Cheap But They Will be PERFECT !!

So how do you stop them distorting when hardened ?

Beavers used to induction harden their leadscrews but they had a final thread gringing process to remove any errors.

See below

Edited By Michael Malleson on 04/06/2013 09:58:20

Edited By Michael Malleson on 04/06/2013 10:16:58

Hi Kev. Can I take it that you will not be doing these nuts and screws in imperial sizes ? For me it would be a matter of having them as a stand-by against future wear.

Mike.

Hi All...Thanks for all your comments, we specialise in all sorts of trick machining including gearbox shafts and machine on a weekly if not daily basis shafts in en39c,then case hardened, we have CNC Precision grinding, broaching, thread rolling, and laser / water jet cutting facilities all in house. These Leadscrews will be correctly, Hardened & they will be well within concentricity (and a lot better)than that of Emco's own Leadscrews. Take A look at the Nuts we have already made, We Produce only the best quality components to some very well known manufacturers & race teams.

If you want cheap ..Then Go Elsewhere. There are plenty of people on the internet who talk the talk.

I am only doing these to fulfill an order for an Austrian Customer, & To Gear Up Our Own 3 x Emco FB2's (student / apprentice training) With Decent Hard Wearing Leadscrews & Nuts. and I don't mind machining 50 spare sets in the process. Material Composition & Certification and Hardness/ Data will be available at point of sale.

These will Only Be Made In Metric...

Thanks for the Dozens Of E Mails, Completion will be within the next 4 to 6 weeks, they will be made with 100% quality regardless of cost / time.

All The Best

Perhaps he ment EN 36C rather than 39C. The steel I use in high strength places is 4140, we'v even had little trouble with it even when welded in fairly high stress areas, it should really be heat treated after welding. It machines quite well, although it is one steel that I use carbide tooling on, to get a reasonably large depth of cut, and feed. Ian S C

Ooops sorry chaps bloody i phone keypad the letters are too close together

hence my numerous spelling mistakes.. Courtesy of a compact keyboard and sausage like fingers !

graham ,,, the last thing i want is the "cheaper option" , if that was the way to go, i would buy the original item from pro mach ! Although cheap isn"t the word there ! Only in the manufacturing process and materials used , certainly not in the sale price!

the material has arrived today, and i' m hoping to make a start at the beginning of next week

watch this space

i have ordered enough to make 100 sets but will have to make a few more nuts to make up the sets

they will be sold as pairs complete with nuts and woodeuff keys

I have one large batch of 50 going to austria and have taken verbal pre orders of 16 i want three sets for our machines here so i will have about 30 pairs to e bay i reckon, I will post a price on here when ive decided the best way of creating the leadscrews and negotiated the a price for having them hardened

we hardness tested the original leadscrews tiday and we were gob smacked to find that the originals were so soft ?! They were tested on our indentec zhv30-s

ever likely the poor fb2 suffered with premature wear and backlash,,,

here is a little quiz for you ,, and if you get it right i will give the first person with the correct answer 30 % discount on a pair of my leadscrews and nuts for the fb2

What material do you think the original FB2 leadscrews were made from ?

and what if any was the hardening process they used back then?

And if you can guess the rockwell hardness numbers thats worth another 10% !!

gotta go its half past midnight

Speak next week as i am away till Sunday

cheers

kev

Hi Graham, Yes i agree 100% the emco is a gem of a machine as i say i have 3 already in my unit, and i have just purchased a fourth from a chap in ireland ! I will collect that next week, when i return from America. this is why I am going to the trouble of manufacturing a vastly improved leadscrew system for the fb2 And this will be regardless of cost or my time ! I have a large machine shop incorporating all types of CNC and manual operations, I have 17 employees all of whom are time served and fully qualified, Albert my oldest member of staff is 72 next month !! Yes i am aware that emco thread rolled their leadscrews, but i was suprised to find that they hadn't used a material that coukd be suitably hardened after the rolling process. I have contacted Karl a very good friend of mine who now works for HAAS automation in America He is operations manager on their manufacturing production line,I have asked him what material they us on their VM s and what processes they use to manufacture their leadscrews, i await his response. It was the same gentleman I contacted before making the nuts last month, i have made them from the exact grade if phos bronze as Haas use for their machines, again regardless of cost !

The blanks to do the nuts were around £30 each. I will keep you informed to progress and will post pictures and information when the leadscrews are completed

many thanks kev

Surely HAAS will be using propiatory off the shelf ballscrews seening as they are the budget range of machines in the big boys world ?