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Member postings for not done it yet

Here is a list of all the postings not done it yet has made in our forums. Click on a thread name to jump to the thread.

Thread: What motor pulley size for ML1 Lathe?
06/10/2019 19:08:20

Hi Chris,

Threads can be cut with a single point tool using the carriage lead screw to set the pitch. There is no need, or point, of using the carriage feed with taps and dies. Single point cutters are cheap, easy to grind and sharpen. There are multi-point inserts available which are also used - probably more in a production environment than for us hobbyists, but available if one wishes to cut threads that way.

External threads can be cut for the full length of the carriage travel, even on small diameter rods . A travelling steady or rod guide of some description could be advantageous for anything which may flex. Internal threads are rarely required for more than the length of an appropriate boring bar with cutter.

Other means of doing the job might be to rough out the cut on the lathe and finish with a die or tap - avoids worrying about starting the thread crooked to the axis (or not perpendicular to the hole), or a way of cutting a coarse thread with a less-heavy workload while using a large diameter tap or die manually.

Yes, with tailstock fixed, a die would have limited travel - but nowt stopping one moving the tail stock at intervals.

06/10/2019 17:55:36
Posted by Chris Vickers on 06/10/2019 16:37:37:

Also wondering if someone has come up with a tap/die holder to fit on the sliding carriage ie for powered threading..along the lines of a travelling steady...?

Many thanks

Chris.

There are propriety (one can make one’s own, of course) sliding die holders to fit the tail stock, which also acts perfectly adequately as a sliding holder for tapping.

Thread: Question from a customer
06/10/2019 17:44:58

..Higher and reduced pressure vessels require different approaches. Long ago a bulk powder lorry tank ( filled by gravity from a silo, unloaded by aeration and blower into a silo) was converted to operate as a large vacuum cleaner to pick up spillages. It was not a simple job, as I recall, due to the risk of implosion.

The classic school lab experiment was that of reducing the pressure in an aerosol can. When evacuated, if it did not collapse as air was removed, it would implode with a slight tap with a suitable edge (a ruler, usually).

Submarines are under increased pressure of one Bar for about every 10m they are submerged.

06/10/2019 14:45:06
Posted by Nick Clarke 3 on 06/10/2019 14:23:52:

Jason's video -

"Pressure on the outside of the can is over 3000 lb" - a bit high and by quoting the force on the can as a whole as pressure misleading to say the least!!

Lbs is the imperial unit for weight, which is a force, not a pressure (S.I. unit of weight is the Newton). Pressure is defined as force per unit area. So that 3000 lbs is likely spread over a couple hundred square inches - at 14.7 lbs per square inch

( not seen the video as it did not play)

06/10/2019 14:37:04

The answer of 14.7psi or 1 Bar is correct and can be ‘verified’ by checking any ‘vacuum gauge - they don’t make them with dials greater than that!

The only way to increase the pressure beyond one atmosphere on the surface is to place the vessel in a pressurised container or sink it in a fluid. Think here of submarines - they have a maximum dive depth after which they are simply crushed by the outside pressure.

Thread: DIY glass fibre pulley?
06/10/2019 11:39:44

Weak link? I would fit shear pins for that purpose. Slipping belts is poor engineering or necessary to cover up previous poor engineering.smiley

Thread: Has to be seen to be believed
06/10/2019 09:59:43

Is there the possibility the vendor is a forum member? Or maybe a forum reader has whispered in his ear?

Thread: Wanted: Shaper
06/10/2019 09:49:08

There is a ‘wanted’ section on the forum. Just scroll down on the right side.

Thread: DIY glass fibre pulley?
06/10/2019 09:22:20

As Clive. 3 pieces of 1”, 4 of 3/4” or 5 of 5/8” as you are writing in inches. Any suitable combination of sizes would work, but the thicker the better I suppose...

TBH, I think I would be converting to a format, other than flat belting, if possible.

Thread: Pulley material
06/10/2019 09:06:44

Fit toothed belt and pulleys? No slippage (rubbing) problem. Cam belts last 50,000miles or more on cars.

Thread: Has to be seen to be believed
06/10/2019 08:56:24
Posted by fizzy on 06/10/2019 00:42:07:

And therin lies my unmentioned dilema. As a professional boiler maker I see how terrible this item is - If put under pressure it will simply distort and eventually fail - it wont explode, its not a bomb and it probably will fail at 15 psi....but its a terrible thing that is being passed off as well made. Do we have a duty of care to point this out or do we say nothing in the hope that nothing bad comes of it?

‘’but its a terrible thing that is being passed off as, well, made.”

That might be a better, more honest, way for him to put it! smiley Well, it was made, but now the description reads as not necessarily well made - which it obviously is not.

Here is what the internet dictionary says. One of them will fit. But basically a seller looking for a mug to buy some rubbish, IMO:

exclamation

exclamation: well

  1. used to express a range of emotions including surprise, anger, resignation, or relief.

    "Well, really! The manners of some people!"

    • used when pausing to consider one's next words, to mark the resumption or end of a conversation, etc.

      "well, I suppose I could fit you in at 3.45"

    • used to indicate that one is waiting for an answer or explanation from someone.

      "Well? You promised to tell me all about it"

05/10/2019 22:17:36

I reckon the vendor has missed out a much needed comma, or two, which could have made the fact that it was made rather more descriptive than the advert indicates. Possibly short on writing skills, but more likely mis-leading on purpose.wink

Thread: Metal expansion
04/10/2019 12:38:27

There are doubtless videos, showing the ‘ball and ring’ thermal expansion school experiments, on the net?

As SOD points out, shrink fitting of parts could not happen if the hole ‘shrunk’!

Invar, a metal alloy, has a nearly zero coefficient of expansion.

Thread: What are members thoughts on Gap Bed lathes ?
04/10/2019 11:14:01

The thread seems to be concentrating on gap beds (per the thread title). The poster was initially also expecting comparison between the chester gap bed lathe at £2.5k and the Warco 290V at £3.3k. No option of a non-variable speed Warco offering and not a gap bed lathe.

My thoughts are that the gap bed will be at a premium, so I would expect the quality/functionality of that lathe is less. That given, the gap bed lathe does appear to weigh in at about 150kg more (does the 230kg include the mass of the stand would be one enquiry). With different bed lengths, that increase is quite considerable - but they have chopped out 75mm extra at the gap end.

I would remember that most gap bed lathes were relatively old iron and very robust. Not so sure about chinese offerings at the ‘hobby’ end of the market.

Might be worth watching the Keith Fenner series of videos on his more recent gap bed lathe (rather larger than most hobby lathes, possibly?) rebuild.

Two different lathes by a long way, so not very comparable, I would have thought. Buyer’s choice entirely. If I were expecting £3.3k quality/functionality I would be checking out both lathes in the flesh, for sure, before making my decision. If not so concerned about the quality/otherwise functionality, and needed the extra swing, then the craftsman is the only option?

Thread: 3 jaw runout problems
03/10/2019 19:40:30
Posted by Richard Cox on 03/10/2019 18:09:58:
Posted by Hopper on 03/10/2019 00:05:12:

Maybe buy a new set of the removeable jaws and hope they too are not a Friday afternoon job?

Otherwise shim what you have with steel shim. Suggested feeler gauge is a good idea.Welding wire is too soft.

Hi hopper sounds like a good idea I hope it is the jaws and not the chuck sliders where would I get replacement jaws from it’s a Chinese chuck on a warco gh1440

I would be asking Warco, as the obvious starting point.

Thread: Leadscrew material ?
03/10/2019 19:32:06

I read this thread as a mis-named feed screw, not a lead screw. It is certainly ambiguous and with the word ‘cross’ included, to me, indicated he actually meant feed screw for the cross slide - not the lathe lead screw. Also, can someone please explain exactly how any feed nut, on its own, is “adjustable for wear”. As I see it backlash simply increases as wear takes place until unacceptable or the nut threads fail.  Half nuts should be adjustable, to a point, obviously.

I can clearly understand the need for a non-square thread for a lead screw, but not for a simple feed screw. Square is stronger than alternatives, cutters are simplicity to make (and it matters not a jot if slightly too narrow as the thread can be corrected by the odd division or two on the compound slide).

Edited By not done it yet on 03/10/2019 19:35:50

03/10/2019 19:32:05

I read this thread as a mis-named feed screw, not a lead screw. It is certainly ambiguous and with the word ‘cross’ included, to me, indicated he actually meant feed screw for the cross slide - not the lathe lead screw. Also, an someone explain exactly how any feed nut, on its own, is “adjustable for wear”. As I see it backlash simply increases as wear takes place until unacceptable or the nut threads fail.

I can clearly understand the need for a non-square thread for a lead screw, but not for a simple feed screw. Square is stronger than alternatives, cutters are simplicity to make (and it matters not a jot if slightly too narrow as the thread can be corrected by the odd division or two on the compound slide).

Thread: Closet Machinist
03/10/2019 19:17:54

Go to ‘Forums’ on black bar towards the top of the page, select ‘website FAQS’. First one.

Thread: Battery charger problem
03/10/2019 17:38:41

As a matter of note, CJ needs to ignore the bit that says 3.7V is fully charged as it is actually the typical fully charged state for longevity of the cell. 4.2V represents the maximum voltage they should be charged to. Capacity is increased between those two voltages, but life-span is decreased.

Thread: Hi from Cambridgeshire
02/10/2019 21:41:41

New? Secondhand? Depends on your mechanical knowledge if secondhand.

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