Member postings for Andy_G

The dodgy set that This Old Tony fettled was Brown and Sharpe, so price isn't necessarily a guarantee of quality.

I have a ~£20 set and find them quite useable.

I believe that's a 1.5 module, 70 tooth belt, 9.5mm wide.

1.5 module = 4.71mm pitch

A 31T XL pulley should be ~50mm OD according to this

However - Are you sure it is XL profile (5.08mm pitch)? My mini lathe, and many others, seem to use 5mm pitch belts (T5 ??).

On the belt pulley - if you are ordering a commercial pulley, check the profile required carefully. Some of the mini lathes use an obscure pitch (maybe not yours) - timing pulleys are available relatively cheaply, so it might make sense to replace both motor and driven pulleys with something more readily available.

On the rigidity issue, I believe that a fundamental weakness of the generic "Mini Lathe" design is the torsional stiffness of the bed - even with the slideways working properly and the gib strips snugged up, the bed can twist in response to cutting forces, allowing the depth of cut to vary.

Once can demonstrate this by putting a DTI between the bed and the work and applying force somewhere that doesn't involve the carriage, compound slide or toolpost .

I have bolted my (similar design) lathe to a substantial beam which greatly reduces this. movement.

Can't remember if I've posted this here before or not.

(Tin hat on)

Edited to add:

This is 42mm dia. leaded mild steel with eccentric holes in it (in fast forward). I don't pretend that it's a masterclass, but it proves that it can be done. Two hands on the cross slide to try and keep an even feed.

Edited By Andy_G on 10/01/2021 13:01:35

Hi - no, I don't. I have seen that some people do this, but it seemed to work well enough without, so I didn't bother.

That's why I use fresh wire every time if using aluminium wire (or at least the non-anodised end of a previously used wire) - when the parts are first mounted on fresh wire, you have bare aluminium against bare aluminium which gives good electrical contact. This doesn't change through the process as the physical contact prevents anodising where the wire and the part touch. (This is potentially an issue in itself as the contact spots won't take colour - Where possible, I aim to mount the parts such that these spots end up on hidden surfaces.)

One only gets problems if the parts move on the wire during anodising or if one tries to re-use aluminium wire that has previously been through the anodising process without first stripping or otherwise removing the anodising (which can be done, if one is so inclined).

One can still get conductivity problems with titanium wires if the part slips during the process - the partially anodised part surface is sufficient to prevent electrical contact with the wire. The beauty of titanium is that the wires can be re-used with just a wipe over with Scotchbrite.

I take the view that one needs to be careful not to disturb the parts during the anodising stage, and by and large it has worked remarkably consistently for me. I've had a few parts drop off their wires, but I haven't (as yet) had one that has had contact problems. (That's guaranteed to happen next time now!)

Andy

Typo, yes (I must have got my home brew and my anodising mixed up [*] - could have been worse!   ).

For the avoidance of doubt: Sodium Bisulphate (NaHSO4)

(I don't know if sodium carbonate would work for the etch, but it may. I'm not too bothered about having 2% NaOH around though - it is a very weak solution)

Tug - yes, cleaning is the problem. I don't attempt to do any cleaning during the process (I can't see it being very successful) . I also avoid drying the parts after cleaning if I possibly can - get it clean & keep it wet!

Thanks all.

Edited By Andy_G on 07/01/2021 11:18:09

[*] That would be sodium metabisulphite!

Edited By Andy_G on 07/01/2021 11:21:20

Thank you!

I must find out how 'nasty' sodium bisulphite really is - I don't think it's as nasty as the acid, but it is still corrosive. I *think* that the chemistry is actually just the same as using H2SO4.

I find it easier to 'spring' parts onto titanium hangers, but I need to get some thicker wire. I found aluminium OK, but I use a fresh wire every time (or sometimes end-for-end them) - stripping previously anodised aluminium wires got boring very quickly! I have had a few parts drop off part way through the process which is very annoying!

Thank you!

The current is low compared to commercial operations, but this seems to avoid a number of other issues (I think mainly heat related).

I did a lot of reading around before I started, and "6A/ sq foot" seemed as good a place as any to start, and because it worked, I just stuck with it. I should give a theoretical 25µm / 0.001" thickness in 2 hours.

I've since become aware that this is probably 'LCD' (low current density) anodising - there is quite a lot of information on it by Caswell.

Some things that have gone wrong:

1) Bad cleaning

Despite (I thought) scrubbing the 'feet' thoroughly, the one on the left didn't anodise properly. I don't think this has happened if I've rinsed the parts in solvent before water cleaning. Cleaning is the biggest bug-bear.

2) Bubbles

If you look at the area on the inside of the rim, there's an area at about 4 O'Clock where the dye hasn't taken properly. This handwheel was held roughly vertical during anodising and this area was at the top. The fine bubbles created during the anodising process have been trapped under the rim which has reduced the depth of anodising here.

3) Not enough anodising

The handwheel was done at my usual 2 hours. As an experiment, I tried reducing the time to 1 hour for the knurled handle. The colour is nowhere near as deep as the handwheel - it might show better here (it doesn't look this bad in real life, but you can tell it's different):

4) Too hot and / or too much current

I simultaneously put a large area of parts in for anodising on a hot day and miscalculated the current by 50%. When the parts came out, they had a brown, crusty deposit on them. I suspect that this was due to the bath getting too hot (it was noticeably warm at the end), but could just have been too much current.

The deposit mostly rinsed off, but you can see staining on the surface where it was:

It was annoying, but I was only anodising a toolpost spindle to stop it getting dinged up.

I've since taken to standing the anodising bath in a bucket of water if the weather is warm or I'm using over about 2 amps of current. I haven't seen the effect since.

The whole process is (IMHO) easy to do and amazingly consistent (barring mistakes) and produces a very hard coating. I encourage anyone to give it a try!

Andy

Mark's video:

Following comments on a recent thread, I thought I would describe my DIY anodising setup.

Traditional anodising uses sulphuric acid as the electrolyte which has become more difficult to obtain, and is generally not nice stuff to have around. I watched a Youtube video by Mark Presling (link below) that showed the use of sodiumbisulphate as an electrolyte instead. (Sodiumbisulphate is readily available as a pH reduced used for swimming pool maintenance.) I have basically copied his process and have been extremely pleased with the results that I have achieved, and how straightforward and consistent it has been.

This is offered very much as a 'what works for me', rather than a 'this is how it should be done'.

This is my setup:

2% sodium hydroxide solution (40g of NaOH granules in 1.96 litres of de-ionised water) for the pre-anodising etch.

Anodising bath with 20% sodium bisulphite solution (750g NaHSO4 in 3 litres of de-ionised water) . Opposite sides of the container lined with lead sheet (electrically linked together).

Spray bottle of de-ionised water for rinsing.

Not shown is an old metal pan that I boil water in for sealing the anodising.

View of lead cathodes with their electrical connection:

I use a lab power supply to provide the anodising current:

The power supply has an adjustable current limit - anodising is a current driven process, and I aim to try and keep the current constant through the anodising process (which would mean adjusting the voltage manually if the limit could not be set on the PSU).

I use a current equivalent to 6A per square foot (=6mA / cm^2) of immersed area and am quite diligent about working this out beforehand. (I have a spreadsheet that I use to calculate what the actual current should be for a given set of parts). Typical currents for what I've done are 0.3 - 1.5A,

I have found that I often need just over 20 volts, towards the end of the process especially. This is a bit higher than the ~16 to 17 volts that Mark Presling uses.

I have only used commercial black dye for colouring anodised parts. The dye solution lives in another sealable container which is immersed in a water bath at 55°C when needed.

The process:

1) Clean and scrub parts under running water. I use fairy liquid and it seems to work OK provided the parts have been rinsed in de-greaser first. I sometimes use Scotchbrite or fine micromesh abrasive to grey the surface. I wear gloves for this to avoid grease on the parts. After cleaning I leave them under (tap) water

2) The cleaned parts are mounted on aluminium or titanium wires which are connected to the main busbar

(The green tape was as attempt to mask the inner surface of that part.)

I still handle them with gloves and keep them wet. I set up my etch and anodising baths outside the house and drop the power supply leads through a nearby window

3) Etch for ~2 minutes in the 2% sodium hydroxide. The parts should be fizzing nicely and white with small bubbles by the end. Rinse off with DI water spray at the end of this time and transfer them immediately to the anodising bath.

(different parts, I know...)

4) Connect up the power (negative to the lead, positive to the busbar carrying the parts) and adjust the current limit to the calculated value. Check there are fine bubbles coming from the parts. I leave them anodising at the required current for 2 hours. They get an occasional gentle swish around to try and shift any trapped bubbles. Rinse with DI water at the end of the time.

5) Transfer to the dye bath if colour is required (I use 30 mins @55°C for the black) then rinse with DI water and transfer to the sealing bath.

6) Seal in a pan full of tap water on a gentle rolling boil for 20 mins before rinsing with tap water and buff dry with a soft cloth.

I am still using the original solutions that I made up last April(?). They just live in their plastic containers in the meantime.

I hope that is of interest,

Andy

Edited By Andy_G on 06/01/2021 22:04:16

It would have been the wrong type, anyway - that's an Abbe refractometer, the one (I think) I have is for a Hilger-Chance - like this:

Thankyou! Yes, it was done at home. I have been amazed at how well it works myself.

It basically follows the process i this video:

https://youtu.be/Z1zT8p7d9Z0

PM me if you want more details, or we can start a new thread.

I got fed up with the mental gymnastics and made a new set of leadscrew collars with 0.02mm graduations! (Chinese mini lathe)

I made new collars because I wanted to make them re-settable / lockable, but you could just make up graduated sleeves to slip over the existing dials if you're happy with them otherwise.

The collars were made from aluminium. Graduations were made using a boring bar on its side and a pointed HSS tool; Indexing with a printed pattern glued to an extension on the spindle and numbers using a punch. I did anodise them afterwards and they're holding up well.

Short term pain for long term gain.

The remaining bug-bear is the 1.25mm pitch cross slide leadscrew. I can see me replacing it with a 1mm pitch one sometime.

Edited By Andy_G on 05/01/2021 23:52:23

Any chance of a photo? I may have a (photocopy) of the manual for one if you are interested. (may be a completely different type though).

Edited By Andy_G on 05/01/2021 17:00:31

I can see them now - must be a problem at my end. Apologies all.

This was the original link that Michael Gilligan posted, but his posts have since disappeared;

**LINK**

From subsequent posts, it seems this is out of date. A note to that effect would have been much more useful than the original posts and responses just vanishing...

Edited By Andy Gray 3 on 02/01/2021 22:31:45

I bought a 7 x 14 brushless lathe from Amadeal early last year. (AMA714B).

Customer service was very good - I had timely and polite replies to a couple of emails I sent, and delivery was swift.

The lathe itself had a true running spindle and straight and square ways. and generally seems to be par for the course for this type of lathe. It was usable as delivered, but in the nature of these things, a little fettling improved it. I've been quite pleased with the lathe - it's done everything I've asked of it. Being the brushless version with belt drive direct to the spindle, the plastic high/low gears are absent. The leadscrew gears are plastic, but under very little stress and haven't been any cause for concern. My only major irritation is that the cross slide leadscrew is 1.25mm pitch which requires more mental gymnastics when calculating how much to feed.

I had an issue early on where the supplied 4 way toolpost had been machined on the skew, but an email and a photo to them had a replacement sent out promptly without any argument (it wasn't hugely better though!). I've bought bits and pieces of tooling from them since and the service has also been good.

If they've got what you're looking for, I would have no hesitation buying it from them.

Is everything else in the workshop on the same circuit as the lathe? If the lathe is on a dedicated circuit, it is possible that the neutral for this has been wrongly connected in a split load consumer unit in the house (if that is what you have - if the neutral from an RCD protected circuit is connected to the non-rcd neutral busbar the circuit will appear to test OK, but the RCD will trip when a load is connected.).