Member postings for Jelly

Finally began to reassemble the little horizontal mill I renovated some 3 years ago.

At the moment it's just a case of trying to get it put back together so I can claim back racking bays to tidy the workshop, as it does actually occupy less space assembled.

I have been able to claw back about half of the space I'd allowed to become occupied, but still need to sort things better to reduce the number of boxes used.

I am seriously considering making a chest to allow me to move my wood tools into the house, although that almost guarantees that I will then immediately want to undertake a complex woodworking project for the first time in a year or more.

I am in agreement on that, even if I wanted VFD converted equipment, it's something I would want to do myself so I understood the modifications which had been made (not so bad on something as simple as the Harrison, but on the mill I've just bought, it would be nightmarish trying to trace undocumented modifications).

Whilst I initially disregarded time, you do have a point:

For me to do a VFD conversion I was happy selling I would probably need to invest a substantial amount of time on wiring the controls, finding a sympathetic way to add speed control potentiometers to the control panel, programming the VFD, packaging it all into an enclosure, and updating the wiring diagrams.

That would only get worse if I was to program it to run the table feed and coolant pump motors (via momentary buttons triggering stepped increases in the power output and latching control signals from the VFD's auxiliary outputs to contactors), although ideally that would need an additional VFD for the auxiliary loads).

The more I think about it, I am not comfortable selling it with a "eh, good enough" VFD retrofit, and doing a good VFD conversion would not be cost effective, so sorting the electrics out for three phase operation and leaving it at that would be best.

Edited By Jelly on 02/04/2023 12:05:09

I think you've summed up the situation nicely there, even 3-4 years ago I wouldn't have been asking the question, because it would have been obvious that single phase would command a higher price for a machine small enough for a home workshop.

Looking at recent sales on eBay and elsewhere however it's not nearly as clear cut anymore.

.

Oh and 2kW, which is firmly in the "chocolate box VFD for under a hundred quid" range.

The DRO is already fitted as it's something I found useful, I will certainly chuck the cost of the DRO onto the asking price but perhaps more.

Can't say without locating the data plate on the motor by shoving a smartphone and a torch into the machine base; I've always run it off 415v 3 phase, but that's not to say it isn't a ∆ 240v - Y 415v motor in there.

Is this implying that:

• if I can convert it to run ∆240v off a 240 single phase to 240 three phase Inverter it will probably make financial sense,
• but if it needs a 240 single phase to 415 three phase Inverter the cost wouldn't be recouped.

I would be inclined to use phosphoric acid (or a suitable phosphoric acid based rust treatment*) on the top of your table, wipe it down thoroughly and then apply a light machine oil or as you suggest a wax.

The Iron Phosphate produced by the rust treatment will result in a dull black finish which is reasonably hard wearing and will retain a protective layer of oil or wax on the surface without being greasy to the touch.

Painting the surface will not wear well, and most likely result in localised rusting wherever it gets scratched, giving you a worse long term outcome.

* Quite a few rust convertor products have a mix of weak phosphoric acid with a varnish or sealant, which is good for metal that will be painted, but would actually work against you when trying to prepare a surface of exposed "black phosphate" to be oiled/waxed for long term protection.

Edited By Jelly on 01/04/2023 22:16:21

I'm looking at selling my Harrison Milling Machine in the near future, and am trying to decide if I will see a return on my investment by converting to single phase before I do.

Ultimately I need to realise as much value as possible to refill the hole in my bank account left by the mill that will be replacing it, but it still has a few electrical kinks that need to be worked out before I could sell it on in good faith (given it was rescued from a scrapheap).

If I'm doing that, it's probably not much bother to install a VFD or switch the motor for a single phase one, the question is if it adds enough to the value to justify the cost of doing it (ignoring my time, because this is my hobby after all).

My experience has always been that single phase machines command a price premium, but it's hard to quantify how much.

There's also a question of if having features like the DRO and vertical head (albeit not the Harrison one) would already put the machine's value up towards the top end of the market, and if offering delivery would push the value up further.

Any advice willingly received.

Edited By Jelly on 01/04/2023 21:54:47

That's looking like a very beefy workbench right there, definitely puts my welding table to shame.

The braces on each leg are a particularly good move.

Regards gluing the top in place, it's actually quite a good idea for flatness and rigidity... But just be aware of how your adhesive reacts to heat if you're planning to use it as a surface for welding on, or it may suddenly come loose.

Used a DTI in the chuck to indicate the MT4 taper of the toolholder in concentric to the spindle's axis of rotation, setting the toolholder height adjuster and the tool X offset on the DRO; massive faff but it only needs to be done once and that's it set for good.

So with that one off awkward setup in place I can now:

• drop the holder onto my toolpost with a drill seated in the taper,
• lock the clamping lever,
• move to X 0.000,
• lock the cross feed and
• start drilling,

all in a matter of seconds.

Edited By Jelly on 26/03/2023 18:20:14

The honest answer is that I don't know why exactly, it's just a practical observation.

The reasons I think it gives better results are a combination of things:

The big one is the comparative rigidity of the setup, my tailstock has to extend out a long way to reach over the cross-slide, which allows for a lot more flex when starting the cut.

The feeding is better all round, drilling works best with a high chip-load and this needs comparatively fast feed rates... It can be hard to turn the tailstock handwheel fast enough to achieve that (especially with nonferrous metal like Alu) but my carriage handwheel will happily move that fast even by hand.

Power feed is then the icing on the cake, because it makes everything very consistent.

Edited By Jelly on 25/03/2023 14:34:50

Almost 6months since I acquired the toolholders to do it, I finally got round to trying drilling with the carriage power feed on the lathe...

Don't know why I waited so long... It's revolutionary!

That was only aluminium, but the action is so fast and smooth, and the hole quality is clearly superior too compared to drilling with the tailstock.

I blindly trusted the feeds and speeds from Machinery's Handbook, and pilot drilled 6mm @ 3200rpm, 0.12mm/rev, then straight to 19mm @ 1200 rpm and 0.3mm/rev, both of which would have been unthinkable for me using the tailstock.

The chip evacuation was also a lot better for the drill maintaining proper chip thickness.

I now just need to get some MT2 and MT3 40mm drill sleeves to fit my holders, so as to maximise rigidity, rather than using MT4 adapters.

I'll give you a very practical example:

Next week a friend is coming over with a short length of 170mm Hastelloy C22 bar, because he wants me to turn him two DN50 blank PN40 flanges.

There's barely enough material to make them and even if I could fit it on my bandsaw it would not cut well or straight, if at all.

So I need to take an 82.5mm deep parting cut through a notoriously awkward nickel-chromium superalloy...

That will stress the lathe enough as is, there's zero chance of me maintaining sufficient or consistent tool pressure and feed rate through a cut that long feeding by hand; at which point Bang! Broken insert, if not broken parting tool, and quite possibly a £900 piece of material ruined.

The name I'm familiar with is the highly unimaginative "Shell Mill Arbour Spanner", although as most shell mill arbours use a nut with four cut-outs, they also get called a "Cross Spanner".

If you're struggling to source a two lobed spanner for it, you might find that a drum key (as used for opening 205 drums) will work on yours depending on dimensions (hard to have a sense of scale, but those look a bit like iso 50 holders) else I'd probably manufacture a beefy pin spanner from some scrap or buy a cross spanner and grind two lobes off.

Edited By Jelly on 24/03/2023 19:40:02

That seems like an entirely unnecessary snipe aimed at making yourself feel big by doing others down for their perceived motivations rather than adding anything useful to the discussion...

He seems to do a lot of high precision small parts where minimising the distortion of the part is key, so it figures...

I get the distinct impression that he's not so much a "YouTube Creator" so much as some guy who is really passionate about precision manufacturing filming things he does aas part of running his business that he finds too interesting not to share, and has got popular for exactly that reason.

My interpretation is that it's actually the grip-tru backplate which he finds useful on that chuck as it allows him to apply minimum required clamping pressure with the chuck then dial things for concentricity in by adjusting the chuck position on the backplate.

Usually my torso...

Unless I'm cutting very aggressively and getting blue/glowing chips, then it's inevitably my face/forearms/the bit of my neck which isn't covered by the collar of my overalls/any other bare skin.

I tend to sweep up what I can afterwards into a big tub, then periodically will lift the duck-boards and shovel up all the remaining chips into the tub just before doing a run to EMR to weigh in scrap.

Actually the thing I forgot to mention is matching the parting blade geometry to the material. It's something we think about all the time for other toolbits, but sometimes gets disregarded for parting blades.

I once did a job for a friend which involved lots of parting off in copper and some stringy horrible grade of brass, it was all a bit grabby unless I used a really slow feed, having quite a few to do, I specifically ground a parting tool with a small negative rake, and like magic I could suddenly feed at a much higher rate.

Similarly I have a brazed carbide parting tool which is preserved for stainless which is much wider (about 4.5mm) with a reasonably positive rake and chip breaker ground into the top face of the brazed insert, the shape helps reduce cutting pressure when taking the more aggressive feed rates needed to successfully cut stainless, whilst the thicker tool gives sufficient support for such heavy cutting forces.

Lathe also provisionally claimed.

Not heard back from my the response to the chap who initially asked about the Mill, so it may still be available if anyone is interested...

Almost always, my lowest available feed rate is 0.03mm/rev, (or 1⅙ thou per rev in old money) so there's never a reason not to.

I will sometimes use manual feed on the first few parts if I'm if I'm making multiples of something small but with a high length to diameter ratio, but that usually means I'm trying to work out how fast I can feed without the part deflecting to select a feed rate.

Edited By Jelly on 23/03/2023 13:04:14

This morning I was enticed into considering upgrading my mill by the availability of a well priced turret mill, which would be a practical nightmare to collect (and undermine my attempts to clear some space in the workshop, but somehow still is drawing me in...

Then spent all my normal evening free time doing design calculations for an emergency job in the middle east, to keep a customers plant running, which is it's own sort of fun...

Nothing like a bit of pressure to make things exciting, I guess I will learn if they were able to build the solution before they ran out of storage capacity and had to press the big red button labeled "Lose $61,000 per minute" sometime tomorrow.