Leadscrews on a Orca 0.3/0.4

Upgrading my orca from T5 to T2.5 (wanted GT2, but could not find the correct motor pulley)
also putting aluminium sleeves on all the idler bearings, and i figured since i had to dismantle the entire printer, i might as well put in some ACME threaded leadscrews 8x1.5, so i was curious if anyone had done it and if you would be willing to share what kind of machineing you did on the ends to secure it in place, did you change up the design of the plates that hold the bearings? did you go up a size?

Hence, if you haven't done a ACME conversion. You need not reply to this thread

I haven't added acme leadscrews but I have upgraded to t2.5 with aluminium pulleys and had a look at what I would need to use acme leadscrews.

For the t2.5 belts I put 16 tooth pulleys on all motors and 40 tooth on the ends of the leadscrews. To fix them in place I tapped the pulleys to m8 and they are very well aligned to the centre of the shafts. I decided to tap the pulleys as an m8 thread isn't exactly 8mm diameter as the threads rounded off at the end. Acme threads don't have this as far as I know so you could treat it as a straight shaft as far as mounting goes, especially as the thread is quite fine. I still use the grubscrews to secure the leadscrews but you also get some grip by tightening the bolt on the other side of the lower bearing.

The reason I didn't upgrade to acme screws is that acme threaded nuts are quite expensive and the nut above the lower bearing takes all the weight of the build platform. I wasn't sure how well the nut would stay in place when tightened and I also needed nuts for the top of the shaft. Basically it was more money than I thought it was worth and I don't have much trouble with metric threads. I have just bought some a4 stainless m8 rod though which I'm hoping will help with waviness in the sides of parts and i'm upgrading to linear bearings.

One other thing that might be useful is looking at 10x2 acme thread. You can buy flanged bearings that will fit in the orca frame but with a 10mm ID instead of 8mm. 10x2 thread and nuts are cheaper and should be stiffer as well.

Pete

pete-theobald Wrote:
-------------------------------------------------------
> I haven't added acme leadscrews but I have
> upgraded to t2.5 with aluminium pulleys and had a
> look at what I would need to use acme leadscrews.
>
> For the t2.5 belts I put 16 tooth pulleys on all
> motors and 40 tooth on the ends of the leadscrews.
> To fix them in place I tapped the pulleys to m8
> and they are very well aligned to the centre of
> the shafts. I decided to tap the pulleys as an m8
> thread isn't exactly 8mm diameter as the threads
> rounded off at the end. Acme threads don't have
> this as far as I know so you could treat it as a
> straight shaft as far as mounting goes, especially
> as the thread is quite fine. I still use the
> grubscrews to secure the leadscrews but you also
> get some grip by tightening the bolt on the other
> side of the lower bearing.
>
> The reason I didn't upgrade to acme screws is that
> acme threaded nuts are quite expensive and the nut
> above the lower bearing takes all the weight of
> the build platform. I wasn't sure how well the nut
> would stay in place when tightened and I also
> needed nuts for the top of the shaft. Basically it
> was more money than I thought it was worth and I
> don't have much trouble with metric threads. I
> have just bought some a4 stainless m8 rod though
> which I'm hoping will help with waviness in the
> sides of parts and i'm upgrading to linear
> bearings.
>
> One other thing that might be useful is looking at
> 10x2 acme thread. You can buy flanged bearings
> that will fit in the orca frame but with a 10mm ID
> instead of 8mm. 10x2 thread and nuts are cheaper
> and should be stiffer as well.
>
> Pete


Sweet, i bougth 16 tooh pulley stock for the motors too, but 44 tooth pulley stock for the ends, my leadscrews cut to length, but without machineing the ends plus 6-flanged nuts where 15 euro plus shipping.

I think i will just go ahead and tap a 8mm acme thread in the pulleys, and fix them like that, but i still need a way of locking the leadscrews in place inbetween the top and bottom bearing, so that there is no backlash. that's my main hurdle, i was considering turning down the ends to a smaller diameter, and finding smaller bearings. and then milling the end where the pulleys goes to make a slot and locking it with this
[www.lrparts.dk] (don't know the english word for them, halfmoon maybe?)