Member postings for david bennett 8

No,the wicks do not go round the bearings. The wicks come up from the oil to the bearings. (It might help to know which model you have)

dave8

Edited By david bennett 8 on 30/10/2022 15:52:20

They look like American style dies. Google "little giant" taps and dies for an example

dave.

No, I meant does your present cross slide look the same as your present topslide regarding the feed nuts?

dave

Edited By david bennett 8 on 08/10/2022 13:17:29

Edited By david bennett 8 on 08/10/2022 13:18:12

Dell, I know this has dragged on a bit,but could I ask one more question? I could kick myself for not asking sooner,but does your other slide look the same?

dave

Dell ,I think I have seen the reason for your confusion. You effectively have through holes for the grubscrews. If you look at the earlier pics you will see the smaller threaded piece has no grubscrew holes. That is what the grubscrews bear against. You probably had them bearing against the topslide casting.

dave.

Dell, the anti backlash idea is not to put a twist in there, but to adjust both sides together (and parallel) to remove thread siackness.

dave.

Dell If you "search" this site for "pultra" ( stripped thread) there is one identical to yours.

dave

Dell, mine is metric,but your nut looks rather long. I wonder if yours was made with the intention of being cut into two at a later date. If not , can you see a purpose for the grub screw holes?

dave.

P.S. use bronze for the nut.

Dave.

All the Pultra cross slides i've seen have the feed nuts made in two parts to allow for backlash elimination The grubscrews adjust the distance between the threaded parts, and the main screws lock everythig together. The thick part is approx. 7.5mm deep, the narrow part is approx.  4 mm deep with a 1.5mm boss. 

Dave. 

Edited By david bennett 8 on 06/10/2022 20:56:58

Edited By david bennett 8 on 06/10/2022 21:23:00

The second link from MichaelG. shows an interesting and usefull accessory (the second from last pic. by "elusivemite" ) It shows a rare adaptor for using 8mm watchmakers collets in a 1MT taper. The one I have has the Crawford Collet logo.

dave8

Edited By david bennett 8 on 17/07/2022 02:00:48

I finished my last clock plates on ever finer wet and dry emery paper (wet), backed by a flat surface, moving the plates in small circles, finally using Vim scouring powder (wet) on the smooth side of a sheet of emery paper.

Edited By david bennett 8 on 22/04/2022 21:33:22

Edited By david bennett 8 on 22/04/2022 21:35:10

Depends on the model.

Pultra P-Type Lathe drawing of headstock?

see above ( from a simple "search " of this site)

dave8

Edited By david bennett 8 on 08/03/2022 18:19:37

Good for you, but please contribute some feefback with before and after measurements, also on the reversed faceplate experiment.

Dave8

Edited By david bennett 8 on 02/02/2022 11:59:47

There might be one way to resolve this once and for all. I am a firm believer that the spindle "register" is not needed. In a previous discussion I was challenged to try reversing my faceplate an seeing how it ran! This flippant challenge was soon resolved with the use of a suitably sized parallel ring spacer between the reversed faceplate and the spindle abutment face( I used the outer bearing shell of an old magneto bearing) It ran and located just as well when reversed as when mounted conventially. If the people who believe in the spindle "register" were to try this for themselves, then measure the run-out both ways and report them hrere, we could resolve it, or at least be able to separate the armchair conjecurists from the engineers.

dave8

John,I too believe the dials were made truly circular, but when they were broken, distortion of their circularity is likely due to the release of locked in stresses. A cast bronze ring, possibly quenched, probably hammered to harden and refine the structure, then machined, would have severe internal stess. 350+ holes in the calendar ring backing plate would add to it. When such a ring is broken, the apparent original center would be in doubt. (I cannot find any data relating to this stress release distortion) ( then there's the problem of centuries of sea-water corrosion)

dave8

Edited By david bennett 8 on 06/12/2021 17:22:07

Edited By david bennett 8 on 06/12/2021 17:31:07

That's interesting. Another example of experiment winning out over intuition.

dave8

dave8

Edited By david bennett 8 on 23/11/2021 02:38:30

Edited By david bennett 8 on 23/11/2021 02:43:29

As a general comment,to summarise, a solar dial with a 365.25 geared pointer, would give a very accurate leap-year correction by advancing  the year dial  one hole  in a 354 hole ring every 4 years.

dave8

Edited By david bennett 8 on 23/11/2021 00:38:52

Edited By david bennett 8 on 23/11/2021 00:43:55

Edited By david bennett 8 on 23/11/2021 00:46:28

Edited By david bennett 8 on 23/11/2021 00:51:43

Be careful here. Pultra 10mm collets are not the same as Pultra10 collets, which are probably 8mm collets.