Member postings for Andy_G

Assuming 1.725 is a typo for 1.75??

1.75mm over 17mm is 5.88° by my maths. (tan^-1 (1.75/17) )

8° would be 2.389mm over 17mm ( tan(8° ) x 17mm ) or 11mm down to 6.22mm diameter.

(Only a few more days of smilie ambushes)

Edited By Andy_G on 03/10/2023 18:45:13

This listing says the operating range is -50°C to 950°C (950°C = 1769°F)

Link

Always been 'gib' (as in Gibson) in my experience, apart from a few (American?) you-choob videos. Sticky-up bits of cranes and the triangular sails at the front of boats are 'jibs'.

'Jigabyte' is just plain weird!

(Although 'gigawatt' is pronounced 'jigawatt' in the film 'Back to the Future' )

Edited By Andy_G on 21/09/2023 18:11:15

I think the Warco super mini lathe follows the ubiquitous 7X pattern, and therefore has a relatively short travel cross slide without T slots.

In order to fit a vertical slide it will be necessary to drill and tap some extra holes in it, either to fit a vertical slide bracket directly or to fit a 'boring table' that can then be drilled to suit whatever slide fittings are necessary.

This was my arrangement:

The boring table is secured using the top slide securing bolts / dowel at the front and an extra couple of tapped holes and a dowel at the rear

The fasteners can be accessed with the vertical slide in place so the whole boring table can be removed without disturbing its alignment.

FWIW, these are the dimensions of my plate - it was made from a laser cut piece of 12mm thick steel sheet with the surfaces 'as is': (I wouldn't bother with the 3/8 dowel holes again)

I sais that this *was* my arrangement: I have since done away with the adjustable angle bracket to try and make the arrangement more compact and rigid (relative term!). A carriage lock is a must!

Although limited, it has its uses:

The cutters are held directly in the spindle using morse taper 'finger' collets and a home made draw bar (suitably long bolt with a simple collar to bear on the rear of the spindle).

I also made a handwheel for the leadscrew to give a 'Z' feed:

Scrap the idea - Make the bed out of rectangular hollow section (something like 150 x 75 x 6) and fit the bolts from inside the section uo into the existing tapped holes in the lathe feet.

It will be lighter and stiffer.

Sorry about that!

(P.S. you also get wifi control...)

Just beware that the ESP32 uses 3.3V logic so (usually) needs a buffer/level shifter to reliably drive stepper motor drivers. (Some people get away without.) Cheap level shifters don't work - DAMHIKT.

This was my approach, but you may prefer a ready made interface:

Edited By Andy_G on 28/08/2023 15:42:30

Not sure if this is what you're asking, but the 32bit ports of GRBL will support up to 6 axes (definitely for the first two, and probably for the third. (Open loop still, though.)

GRBL_ESP32

FluidNC

GRBL_HAL

GRBL_ESP32, although no longer actively supported is *very* compatible with 8 bit GRBL and its senders. Both it and FluidNC can be compiled in the arduino IDE.

FluidNC supports software configuration, so you can make machine changes without having to recompile. It will play with many of the Gcode senders, but not my favourite one (Openbuilds Control).

GRBL_HAL needs to be compiled in the appropriate IDE - I haven't used it as I can't be bothered to install yet another IDE, and the web based configurator has limited options.

GRBL_ESP32 works well for me on a 3 axis machine with the ability to run a second spinde (laser + rotary) and a 4th axis without having to change any firmware or wiring.

CAM is the big hurdle for 4+axes.

Edit: I should say *cheap* CAM is the big hurdle...

Edited By Andy_G on 27/08/2023 22:18:37

Just one: When you finish the cut, back the tool out slightly before returning to your start position. A lot of the marks look like you're winding the tool back over the work without doing this, giving the coarse spiral marks.

They could probably be either, but those don't look (to me) like they have end cutting ability that I think a slot morticer would need (but there are probably more types than I know about).

M10 internal seems to be used on all sorts of industrial routers (hand or bench), morticers, etc.. Seems common for automated routers for PVC window frame construction.

Have a look for 'Rotox' cutters: (Example )

(Other makes using the same fixing are available).

Internally threaded router bits.

Like these

I knew I had used one as part of my engineering degree, but was struggling to remember what for - that was it, though: The lab had a large, single cylinder horizontal gas engine with an indicator fitted and we used the planimeter to measue the area of the indicator trace when analysing its performance.

Never used one since!

The O-ring isn't particularly critical - find one with an ID that matches the bearing OD (within a few %) and has a section diameter that is less than ~25% of the bearing width.

Cut the groove in the housing to ~90% of the O-ring section deep by somewhere between ~125% and ~150% of the O-ring section wide (not critical). The groove is roughly centered on the bearing location.

(The groove could be machined in a different setup to machining the bore because any sight lack of concentricity doesn't matter.)

Sorry, I misunderstood - I read it that you had a separate high speed spindle, offset from the mill spindle, with some sort of mounting bracket held in the mill collet - my apologies.

Have you checked the runout of the taper on the ER11 collet extension with respect to its own shaft? I have had a couple of shockingly bad ones and one very good one (roughly similar prices). Similarly, 'cheap' ER11 collets vary widely in their ability to run true.

Could you put the drive pulley on the rear of the bearing arrangement so that there was less overhang at the front bearing? IMHO, it's well worth trying to minimise tool overhang, to minimise the effect of spindle runout / lack of straightness. The smaller the tool diameter, the better the runout needs to be.

This is the arrangement for a toolpost spindle I made using the good ER11 collet extension. It is driven from the rear by a timing belt pulley:

The motor is mounted piggy-back:

I wouldn't use the double row A/C bearing again (it still needs to be preloaded to remove slop - I didn't realise until after I'd made it). If I were to make one using an ER collet extension holder again, I'd probably use a similar configuration, but with a single bearing at each end (maybe A/C or maybe plain ball bearing, depending on likely loads & budget at the time). I think it would be a compromise compared to machining a spindle to one of the designs above, though.

(Sorry, I didn't intend to monopolise this thread - it's just a topic that I have given quite a bit of thought to over the last few years!)

Edited By Andy_G on 28/07/2023 18:36:00

The problem I had with the aluminium housing was that the preload reduced / disappeared when it got warm. If the preload was adjusted to 'take the slack out' in this condition, then the spindle almost seized when it cooled down.

This was with a solid spacer between the inner races (a circlip for various reasons) and an adjustable nut to preload the outer races against each other:

Unless I'm missing something, the same arrangement with a [low expansion] ceramic housing would do the opposite: i.e. preload would tighten up as the temperature increases.

Incidentally, something to consider is that matched pairs of angular contact bearings suitable for face to face mounting are available, fairly cheaply, as spare parts for Chinese made CNC router spindles. Face to face mounting takes the expansion of the housing out of the equation. The quality of the ones that I have bought has been pretty good.

Edited By Andy_G on 28/07/2023 15:00:04

Doesn't run a bicycle repair shop on Anglesey, does he?

He used to be a General Manager at a place where I used to work.Technically, he was in the Royal Marines, but never made it through basic training. Didn't stop him regaling people with his gruesome tales of daring-do and unfeasible feats (it turned out that Len Deighton must have been with him for most of them). Completely brazen / psychopathic personality.

I don't think there's any public record that can be used to verify this sort of thing (we looked very hard once suspicions were aroused). A real ex-RM knew through his contact that this person was a Walter Mitty, and in the end 'whistle-blew' to our mutual employer. The employer responded by disciplining the whistle-blower for breaching confidentiality! Walter Mitty was also disciplined, but not sacked!

It's a funny old world...

This is a powerful argument (in my mind, at least) for making the tail bearing OD smaller as it allows all of the bearing locations in the housing to be machined in the same operation, giving the best concentricity possible with given equipment. (They don't need to be *especially* accurate otherwise - the tail bearing bore is probably the most critical: to allow float without slop.)

I'm not sure what material Steve is thinking of for the housing, but in the design with a spacer between the inner races only, I would suggest that the housing be made of steel, rather than aluminium, in order to avoid variations in bearing preload as the spindle warms up - I tried something similar with an aluminium housing and the temperature effect was remarkably noticeable.

This will be the Rolls Royce of spindles when it's done!

I made an ER11 spindle of a very similar design on my mini lathe. I was very pleased with the way that it came out – I couldn’t detect any runout in the spindle itself with an 0.002mm indicator, and about 4µm TIR on a tool in a decent quality collet.

This was the sequence I used:

With the stock held in a 3 jaw chuck, I machined the tail end as far as I could and cut the threads for the nose bearing clamp nuts (on my design), but only roughed the bearing journals.

I then flipped the part around and held the tail end (centred) in the 4 jaw chuck. The other end was supported with a fixed steady while it was centre drilled so I could use a live centre for support while machining the outside of the collet chuck and cutting the collet nut threads.

I used the fixed steady again, without disturbing the part, to bore the collet recess and cut the internal taper for the collet. That was the bulk of the machining completed.

I then chucked a short piece of brass and cut it to match the collet taper (while the compound slide was set to the correct ER taper angle).

I could then mount the spindle between centres, using the collet taper to support the ‘nose’ end of the spindle on the brass live centre with a dead centre in the tailstock. This setup was used to machine the bearing abutments and journals.

The journals were left 0.01mm oversize and then lapped to final size. I was very pleased that I managed to get them both pretty much spot on – just a few microns above nominal.

There's a bit more description of the whole thing on the page I linked to in a previous post.

I'm sure that there are other ways of doing it, but that's what worked for me.

Yes - my comments would only apply to the case where you have a nut retaining the bearing only (the design in the post on 24/7 15:02).

For the latest iteration, I don't see much point in threading the pulley *and* fitting locknut. As you say, the drive torque will keep things done up.

That nut can be done up tight, but it should be left hand thread for a clockwise spindle by rights (or backed up by a locknut).

I think that the concern for the front clamp ring is because it will be used to set the bearing preload, so will need to be locked at the chosen position, rather than being done up tight.

Edited By Andy_G on 25/07/2023 10:01:17