Member postings for JasonB

Final option would be to buy a cheap 9/16" nut so the lathe can be used then machine off the M12 thread from the ARC stud, drill & tap M8 and then fit the ARC stud in place of the LMS one and use the flanged ARC nut.

As I said I think it is 14mm x 1.5 on th etop of a 9/16" shank to match 9/16" hole in post. If not it's 14mm all the way to the bottom shoulder and a looser fit in the hole

Michael as my post above Ketan is saying they supply a stud of 9/16" dia shank, top is reduced and theraded M14 x 1.5, bottom is reduced to 12mm and threaded M12 coarse.

As the hole in teh toolpost is 9/16 you want a nice close fitting 9/16" shud shank for repeatability.

No Porkies being told

I'll check with Ketan tomorrow but I think what is on their site is the stud is threaded M14 x 1.5 at the top and will pass through the 9/16" dia hole "D" in the toolpost. ARC have a specific post stud to screw directly into the metric thread on the SC4 topslide and as all other threads on the lathe are metric they also specify a metric thread for the top.

I would have thought a stick on magnetic strip would not overpower the Proxxon and the read heads are quite small at 10 x 15 x 35mm. A cunning engineer like yourself could probably hide the scale within the dovetails rather than mount it externally which will be what I will do on teh Lateh cross slide if I ever decide to fit a DRO to that.

I'm not sure how important it is to have a flanged nut, you could turn up a thick washer and use that in place of the flange with a plain nut on top, not too expensive

My Jowitt is also on here as is the Muncaster No1

Just tried his calcs for my 2" fowler boiler which has 1/8" solid rivits @ 7/8" spacing and WP of 100psi. His calcs say I would need as cross section of 0.022sq in using a factor of safety of 8 but an 1/8" stay only has a CSA of 0.012sq in

The problem is that if you work out the loading on a stay threaded 5BA @ 120psi it is not strong enough at 1/2" spacing and comes below Harris's suggested factor of safety

Using his calcs a stay supporting 120psi @ 1/2" spacing needs a Cross section of 0.012 sq in. but the core dia of 5BA is 0.0073 sq in this falls below his suggested average safety factor of 8 ( 25000/8 = 3125). The 6BA at the same 1/2" spacing would be outside his safety factor range of 6 to 10 completely.

His spacing table does seem fairly linea going down 1/8" spacing for each 1/32" drop in plate thickness. So you could say that for 1mm / 0.040" plate the spacing of 1/8" stays would need to be about 10mm, so 7mm between stay or tube edges. Just need to arrange enough of your 10mm tubes to meet that spacing withing the 50mm or so dia of teh end plates. Probably needs a ring of eight tubes around a central one so 9 tubes in total, they will be stronger than stays.

Actually Dave you can bring a blinted milling cutter back to life by roughly grinding a 45deg chamfer on each corner particularly if it has just been used for shallow facing cuts. This is not painful to the pocket and can simply be done on a basic bench grinder or with acoarse diamond slip.

I suspect what has also helped with Andrews finish is flood coolant to clear the swarf so none getting cought under the cutter and swirled around. A constant power feed also helps give a uniform finish.

The only downside to flycutting (and face mills) is that you want your tram reasonably good to avoid a concave surface

Its a collet chuck, popular from China before ER became the main choice. Uses a similar style collet I use done when I first got my X3 without problem and do still use it on the odd occasion as the nut is smaller dia.

Although under the same stress being flat the same calculation for the barrel can't be used so there is still no calculation for flat plate thickness which is what the OP wanted.

If you just worked it out based on what diameter and number of stays were required and populated them equally about the surface there would still be a risk that the material could deform as the spacing may be too large even though there are enough stays.

It is interesting to do Harris's stay calculations based on 110psi being the average of what he says the table relates to, Only problem is 5 or 6BA stays at 1/2" spacing would not be strong enough! and there is certainly a bit of pick whatever safety factor you fancy.

Edited By JasonB on 23/09/2023 07:27:00

If you think it will unscrew with Loctite then add a grub screw in from the side, even grind a flat on the screw head for it to bear on.

It was going so well until.............................

Just had a look at John Haining's "Countryman's Steam". Much like the others he goe sinto detail about barrel calculation sbut not flat plates but he does say

"As a rough Guide for those that do not want to become too involved all flat stayed surfaces should be at least 1/3rd thicker than the barrel material"

So why not take that as a fact that your 1mm material is not ideal. You can then just use Harris's table for 16swg material, or go with Duncans suggestion of tube spacing in 16swg material etc. It will be a lot easier to drill and solder without the risk of overheating

If you are not careful using very thin plate will result in having to use so many tubes to act a sstays that you will start to reduce the water volume within the boiler so much that you will end up with  a flash steam boiler

Edited By JasonB on 22/09/2023 11:18:33

Harris book says the stay table is for pressures of 100-120psi, last line above the butt strap drawings

Noel, can you say which page the calculation is on in Harris's book as like the OP I can't see one.

As far as I can see it tells us how to calculate stay diameter , gives a table for spacing of stays for various material thicknesses but not the thickness the OP wants to use. No indication of how the table was arrived at.

I do use Half a lot as I tend to work from the ctr of most parts so find one side and zero, find the other and half the reading. Also averages out the two edge finder positions rather than using one edge position only

On parts that may have a lot of features I may "mark out" with a sharpie but don't count that as proper marking out, as Pete says it is just to help ensure the orientation is correct and helps avoid silly errors like positioning a 6 hole PCD north south rater than east west.

As for proper marking unless it is something like sheet metal than I'll use a height gauge rather than a rule if possible and any punching gets done with an optical ctr punch and if that is not right I'll pull it over with a hand punch. This is mostly reserved for ctr locations that will be going into teh 4-jaw lihe eccentrics or rod holes in valve chests which can then be set to run true with a dti. I see no point in doing it this way if the part is going on the mill when I can pick up the edges with an edge finder and then use the DRO to position the hole. Soemtimes I will even position a ctr drill hole using te hmill and then transfer the work to teh lathe so eliminating even more marking out.

Thats a generalisation of how I work but depending on the part may use other methods as suits.

Then do as David says and visit Alibre's web site and download the new version from their, I've done it that way several times in the past but last couple just when the program prompted me. Just select Atom3D from the list and then click the large icon that appears.

I would suggest you try and set aside an hour or two a week to use Atom that way you will be les slikely to forget things and have to relearn them and may make some forward progress rather than having to keep taking steps backwards to relearn.