Member postings for TimS

I thought i should post about the results of this thread as it helped me a lot i bought 2 lengths of each right and left hand 16x2mm from

http://www.metallbau-pietrzak.de/shop/index.php

i ordered them on a Sunday (a bank holiday Sunday) and they arrived nice and promptly on the Wednesday in fantastic condition; strapped to a sizeable piece of wood; wrapped in bubble wrap and in a custom box... it would have been fairly hard to damage them with this level of packing protection

price wise they were under £20 a meter which seems to be very reasonable to me

the screws also seem to be excellent, they are very smooth to the touch and look much better made than originals in my warco mill and even on my warco lathe

i didn't buy any nuts to fit them so i cannot comment on their quality (i plan to machine a section of each screw to make a tap; if that doesn't work i'll no doubt be on here asking for another option )

the only slight downside is the website is all in German; i used goggle translate on both the site and the emails i received with no problems; there are some graphics based buttons which didn't get translated but they had arrows so weren't too difficult to decipher

as you can probably tell i am rather pleased with the outcome and wanted to thank all of the contributors in this thread for making such a difference in my being able to locate exactly what i wanted

TimS

What about casting a nut from epoxy? you might be able to use the existing void as a mold?

alternatively you could push the old nut into plasticine or clay? as a last resort lego or carved wood could do the same job

TimS

its a good thought michael; i was going to convert it to metric but i have never really got on with it, the replacement motor is under powered and has no reverse, i dont trust it to turn parallel and fixing all that plus a leadscrew upgrade would add another project to do before i get to the one i want... 3 steps from what i want to do is just too many

on top of that i can get the screws i need for the same price as the blank materials and the new leadscrew

at least with the mill i am sorting it and it will be a permanent upgrade that i can use for all sorts, i am likely to sell the ML7 when i get half a chance; its 1940's from what i can remember and i think is all original... it needs a loving home and i'm a metric guy

Tim

Hi MichaelG; the only way i could make the screws would be on the lathe; I've not done much thread cutting so it would be fun to say the least; that and the fact my metric lathe (WM180) wouldnt cut a thread long enough in one go... i was trying to work out if you could cut half the length before moving the rod to cut the other half... the only way i could come up with was to fit a nut in the tool post and unscrew the already cut part to allow machining of the rest... how accurate that would be is up for debate... i could do it on one of my imperial lathes but in all honesty i dont trust them for accuracy (a 19x18 and an ML7)

the most amusing part for me (regarding articles) is that the mill overhaul is to get me to a stage where i can work on a project which i am writing an article about... i may even get an article out of part of the mill modifications that i have never seen done before... so it may be a case of watch this space

Hello again Niko; your final link seems to have answered the original question; they do left and right in the sizes i need, sell nuts too and the prices are blummin great

i hope to place an order fairly soon (well as soon as i have considered any other project that could ever need a leadscrew )

Hi Ian, thanks for the info on DRO's; i need new longer screws regardless of pitch and i would like them to be as accurate as possible; i think 2mm screws are a compramise that will allow good fine control as well as not making distance moves too painful;

as for screw accuracy most places seem to quote better than 0.1mm per 300mm; i dont know if thats good or bad but it seems fairly standard regardless of the pitch; i know a DRO will be better than this but i think i might opt for CNC first

Hi Martin thanks for the extra info... i may well opt for them if i cant buy them by the meter... and a link below has helped with that

Hi Les, the problem with a straight leadscrew swap would be the length problem; i need screws quite a bit longer than i think even an X3 would allow

studding was looking promising for a while but getting it in left and right hand was another set of fun and games

as for DRO's i had considered them instead of different pitch screws but as i needed longer screws i thought i would swap to make my maths simpler and maybe fit DRO's later i do worry about rotary encoders only showing screw rotation and not actual distance travelled... but it would seem that i am a worrier

Hi Chris; many thanks for the link; unfortunately they don't do any in 2mm pitch should i be asking the reasons why they aren't available?

perhaps i should be asking what pitch leadscrews other people use on smallish milling machines? after a 2mm pitch the most obvious (to keep the maths fairly simple) would be a 4mm but a quarter turn per mm seems quite inaccurate

am i imagining a problem with coarser screws on small work?

should i be looking at even finer screws than my 1.5mm original?

or should i start practising cutting 2mm acme/trapezoidal threads myself?

Tim

Hi Russel i will scour their pages fully later; last time i checked they were out of stock of some but maybe they have got some more in

John the reason for the change was mainly due to my terrible maths abilities; 1.5mm gets a bit complex for me; i needed to extend the length of the x axis screw as it only gives me a tiny amount of travel relative to the slide length so it seemed sensible to change to a longer screw of a more sensible pitch

i had considered belt drives and pulleys but it seemed a bit complicated when screws of the right sizes are made (just not necessarily available)

i have checked with Marchant Dice and they do make a 12x2 in right hand so i may use that on the x axis; make the y axis screw myself (perhaps with a Arc Euro 2mm Nut) and opt for a coarser pitch for the z axis to replace the god awful fine feed... would be oh so nice to find all the parts in one shop but unless i can find one i am stuck with a mismash :/

Hi Jason, i hadn't found any ball screws with a small enough pitch to strongly consider them; i have looked at the link and the prices are so high to rule them out completely; another reason i ignored them is because i thought ball screws shouldn't be used on manual machines due to the lack of holding resistance?

Thanks for the extra info Martin; i share your concern with accuracy but the longest threaded portion i will need is 380mm (just slightly longer than the max length my metric lathe will take) they are made to DIN 975 so i dont know the standards for that; but a quick search showed that you can get trapezoidal threaded M16 which i admit would be better

so now to see if i can find an even more specialised thread form of an already nearly impossible to find item... is the reason they aren't readily available simply because people make these parts themselves or is it the advent of CNC reducing the need for finer pitch screws?

thanks, tim

Thanks Tim i might look out for them if they do left and right

and many many thanks speelwerk/niko; they do a thread that would suit perfectly... ill have to look at shipping but i had not considered being able to buy studding in left and right hand

everything i have heard in english is the use of pitch to represent what they have called slope; however i can understand what slope means so it could well be an auto translation issue... strangely i would never have even considered the use of the slope for pitch so my searches would have never shown the site you suggested... so thanks again

i haven't tried Halifax Rack & Screw roy but i will send them an email... the usual problem of non standard items is cost

i will also have a look at the manufacturers you mention martin to see what they can offer; i had skipped them under the presumption that to my knowledge they all came with 1.5mm screws

Hi, i am looking to replace the lead screws in my X2 Mill with reasonably priced alternatives of a different pitch, instead of the existing 1.5x15mm i would be a lot happier with those of a 2mm pitch

i have managed to find 2mm pitch screws but the largest diameter is 12mm; which i dont think is large enough given the 15mm diameter of the current set

does anyone know where i could find some screws between 13 and 16mm (the exact diameter is not as important as the pitch) i will need both left and right handed screws and nuts... i have checked Marchant Dice, Zapp, Abssas and Moore International with no joy... is this something i am going to have to make myself? i assumed that they would be available as so many lathes use large diameter small pitch lead screws for the carriage feeds

any help would be greatly appreciated and thanks in advance

Thanks Michael and Michael; there isnt so much of a design problem as just an alternative; the same size square bar has more mass than a round of the same diameter but obviously makes the machining more challenging... and opens me up to a whole load of extra work and potential errors

essentially i can get by with one flat side so to produce this accurately i was going to:
1. turn the whole outside of the bar and boss at one setting (or between centres)
2. bolt some sacrificial pieces to my Mill and cut V's into them in situe
3. mount the round bar in those V's (thus fixing any alignment issues with my mill table and ensuring that everything runs true)
4. Mill the top face to size and do any other work to finish it; then remove once its finished (i figured doing it all at once is a good way to ensure everything is all on the same plane and i have none of the problems of setting it all square again if i were to remove and remount)

its probably now aparant that i dont trust my abilities that much but i wanted a way that would introduce as few potential errors as possible... and the only way i thought of ensuring that is to do it at the same time without the need to clock anything

if i have missed something that will cause me problems feel free to say as this is one of the only routes i knew that could ensure accuracy without having to measure each mouting etc etc. obviously i would clock it and not trust i hadnt made any mistakes in the setup... but its more confirmation than location

I'm sorry that this becoming a thought exercise is a let down but it has become very obvious to me that this is outside the scope of my machining abilities

a piece made from square bar would be much better than one made from round but i know i can solve any centre mark issues with the first cuts by turning the whole surface of the bar in the lathe, making a boss at the same time so I end up with an exact piece that i know will be both parallel and concentric (assuming tailstock alignment)

if i had stuck with using square then i would need to accurately machine the 4 faces of the cast iron bar to remove the scale in the mill, hope my machining skills are good enough to ensure that i end up with an exact square, centre mark the ends accurately, drill precise centre points and do my best to get a level of accuracy i dont think i can achieve, turn the boss; and hope all is accurate... i also dont have the kit or any experience with using precise measuring equipment to ensure that all is well with a square piece... round however makes all of that a lot simpler, and for me thats quite important; i am willing to sacrifice a far more ideal shape for the guarantee of precision... and precision is why i asked this question in the first place

apologies again if i have wasted your time

Thanks for even more replys i haven't had time to process all of them and as regards to accuracy thats a very good question, i hadn't actually considered that as this is my first really precise job... and i dont much like numbers so only tend to think of them as a last resort :/

using square bar was more of a thought exercise as i had planned on using round (which would seem to make the whole exercise a lot simpler) i usually over complicate things or overlook the obvious so i thought this would be the place to ask... and as usual i pick a question with multiple answers all of which spawn even more questions

however reading all this has brought to my attention that my problem could well be more psychological than technological; a hammer and centre doesn't feel precise... maybe thats just lack of experience but thats why i asked the question; i had never seen it in a book... well not one with bar that didnt fit through the headstock so guessed there was a good reason for this

thanks again and i will keep reading all your replys tim

Thanks for all the suggestions; i have just received my copy of "Workholding in The Lathe" so i will give that a read for some more ideas

i dont have a DRO or a mill big enough to hold it for drilling as for turning a boss with a chuck there i had planned to turn down a small section that could be held in a fixed steady while i drilled the accurate centre hole

i wonder if i swapped a flanged collar for a way to hold a smallish 4 jaw chuck in the fixed steady i would then be able to drill the centre with the tailstock for turning

i might also do a few experiments to see how closely i can get a punched centre hole... my only worry is using that centre mark to drill a hole big enough for a dead centre... i might have to drill it by hand and generally i am utterly useless at getting them anything like square

thanks again

Hi, i am after some pointers on how i can precisely mount a large and long square bar in a lathe for turning?

i have a 300mm length of 70mm square bar that needs a boss turning on one end, the boss needs to be very accurately centred and running parallel with all the sides.

The only method i can think of (with the kit i have) is to use 2 independent 4 jaw chucks, one in the head stock and the other freely rotating in a very accurately aligned tail stock which would allow me to adjust both ends precisely

is there another or better way of doing this? i dont have a tailstock chuck so will need to make that however i am sure there are other probably better ways of solving this problem

thanks in advance ) Tim