Member postings for old mart

It will indeed run ok as it is, but the spindle speeds are halved from its original design.

I was waiting for this thread to pop back up rather than be accused of scaremongering. We are not out of the danger yet by a long chalk. North Somerset has one of the lowest numbers of CO19 in the country, but I have had some rather worrying news about Weston General Hospital. They are currently down 40% on staff, no new admissions, 200 CO19 patients and the A&E is closed. All emergencies are being taken to Taunton or Bristol.

My interpretation is that Harrison chose a single phase motor running at a lower speed to directly replace the standard three phase one. Even the pulley size was unchanged. They may have chosen a slower single phase motor to retain most of the torque, but at lower spindle speeds to sell their products to people with only a domestic single phase power supply. 1.5 kW (2hp) single phase motors of 4 pole running at 1360rpm run at 9.3A full load with a start current of 32A. As mentioned by Clive, the lathe has a full range of mechanical speeds and it might be better to run the lathe on single phase having a suitable dedicated spur.

Just in case you have not heard of Lathes UK, here's the page for the M300, it mentions the single phase powered versions and the 1.6Kw of the standard version. The nearest equivalent VFD's and motors would be in the 1.5 Kw power (2 hp) which would be lower cost than my 2.2 Kw price estimate. The power for this size would be 16A which would simplify the connections, needing only a permanent switched wall connection from a radial. If you were looking at the IDS inverters in that range, be aware that not all of their products have the Quick Start Guide included, and avoid the one's that don't.  http://www.lathes.co.uk/harrison-m/page2.html

Edited By old mart on 26/05/2020 20:29:11

Edited By old mart on 26/05/2020 20:29:57

http://www.lathes.co.uk/harrison-m/page2.html

Edited By old mart on 26/05/2020 20:30:25

Edited By old mart on 26/05/2020 20:31:05

Edited By old mart on 26/05/2020 20:31:42

I did notice that the input current for an inverter of this size is 22A. This means that a dedicated spur of 4mm minimum wire with the associated connections would have to be factored into the cost.

Niel, if there is room for 24 three millimetre screws, that would certainly take care of any shock loads that might happen.

The outlay on the lathe is much greater than what upgrading the motor in the future would cost, and the lathe is usable in the meantime.

Try looking up Inverter Drive Supermarket, they have masses of stuff including these for example:

WEG CFW300 IP20 2.2Kw @£161.  IDS have a quick start guide which makes setting it up understandable and is worth its weight in gold.

TEC IE2 2.2Kw 4 pole 1440rpm motor @ £154

Edited By old mart on 26/05/2020 17:34:30

You can transmit white light through optical fibre, as well as some infra red and ultra violet, if that is not the complete spectrum, I don't know what is. More than 80 and with usable separation and bandwidth.

A direct mount has one drawback, it cannot be adjusted like a separate backplate which can be turned true after fitting. A backplate will give you a choice of er or 5c, or both.

Bare aluminium should be shotblasted to give a bond for araldite, chromic anodised is much better for adhesion.

The joint between the handle and the shaft needs to be strong because of the force needed to cut these large threads.

What about using small screws through the SS and threaded into the aluminium? The wall thickness of the aluminium looks like 5-6 mm, so 3mm screws would probably work, you could fit dozens in there, that would safeguard the telescope.

I now have up to 223 Mbits and the only benefit which I have noticed is the speed which an ISO of Windows 10 pro 64 downloaded. Most websites don't seem to be any faster, probably because of their limitations. Big businesses can use these speeds as they have thousands of connections simultaneously.

At the museum, we have a large drill mill which has 500mm X travel, and a Tom Senior light vertical with a slightly smaller bed. 100mm vises are about the optimum size, and we have a pair which can be used together, but we also have one of ARC's 5" vises which opens much wider than the smaller ones. I think the 5" is the biggest that fits without being too big, and the swivel base is only used very occasionally. A 6" vise would be too big and too heavy for my liking.

Edited By old mart on 26/05/2020 14:10:03

Start on the smaller components and expect failures. That way you haven't wasted as much material and will gain the expertise to tackle the more complicated parts.

Its all about practice, keep measuring things of known size to get the feel of your instruments. Consistency when measuring is something which will come eventually.

The diameter verses length ratio is not in your favour, as already mentioned, a centre is needed. For this small diameter a thin extended live centre would have the best chance of not fouling the tooling. Every cut you make removes a larger ammount of metal, so the depth of cut should get less each pass, the last cuts should be as low as 0.025mm (0.001". To give more clearance for the centre with such small diameter threading, the right side of the tool can be ground back quite a lot. You could also add 6mm to the length and take that down to the core diameter and cut it off when the thread is complete. You will need some small centre drills as well.

Keep practicing, you are nearly there.

I see your point about the limitations of squeezing the thread, Clive, and if I was needing to produce that thread in a nut, I would look closely at the threading insert to see if it could be modified to allow the tip to stick out another 0.1mm. Maybe just getting a good close fitting starting size before sawing the slot would be enough. The design is rather poor, just enough to get past the guarantee.

The inserts for 1.5mm TR are available from Cutwel in 11IR and 16IR , but I don't know whether they have a minimum order of one insert or not.

https://www.cutwel.co.uk/threading/indexable-threading-single-point-threading/trapezoidal-threading-inserts/tr-trapezoidal-internal-right-hand-for-aluminium-and-non-ferrous-vk2-grade-vardex

Edited By old mart on 25/05/2020 18:19:19

There are several different makes of these belts, the type with the tee shaped end of the links is the easiest one to work on, you just turn the tee in line with the belt to remove and reconnect and turn the tee so it faces across the belt to run. It is called "nut-link"

**LINK**

My best calculations are bore 14.8mm and total cutting depth from there +0.75mm. At that point, use the leadscrew as a gauge, you will have to remove the tailstock and move the tooling out of the way.

The basic dimensions are thread depth = 1/2 X pitch.

Starting bore 16mm -2 x thread depth + 0.1 x pitch.