[Buoyen]

Hi Craig. Does your spindle manufacturer have a website?

[joeavaerage]

Hi,
yes the manufacturer does have a website. I did not buy off the manufacturer, I bought off Ebay from a guy in Vietnam. The spindle is new, but I would guess old stock. There is no exactly matching spindle on
the manufacturers website, but one or two which are very close. I can only guess the Vietnamese guy bought them cheap somewhere and is then on-selling them. I paid $2000USD (including shipping) for the spindle
and the ten tool holders. I think that is pretty good value for money.

https://www.haozhihs.net/

This is the close relative spindle to mine:

https://www.haozhihs.net/show.php?id=611

This is the guy I bought from:

https://www.ebay.com/sch/i.html?ssPa...n=nhatson.elec

Just as a word of caution, when he sent the spindle he declared it as a gift and for a much lower value, and NZ Customs seized it. I was very lucky to talk them out of seizing it for good with no compensation....no nothing.
DON'T DO IT!!! If you do buy off Ti, then get a proper invoice and do the right thing, I came that close to losing a $3500NZD item.....

It seems that there are ads all over the place for Chinese spindles at this time, and all are very competitively priced. My guess is that the major slow-down the Chinese economy is suffering means that many manufacturers are struggling
for sales and therefore advertising like mad and cheaply. I don't wish them any harm however I can say its good news for us.

Craig

[phomann]

Hi,

Yes the price of the ATC Chinese spindles is coming down.

Since my spindle controller has decided to blow itself up, I need to attempt to repair it. If not I’m seriously considering one of these.

3.2kw 12000 rpm BT30 engraving machine pneumatic tool change spindle, ceramic bearings, finishing high torque spindle
https://a.aliexpress.com/_mNhELmI

With the addition of a VFD, and new tooling it would not be cheap. At the moment I’m rather committed to the TTS tooling system.







Cheers

Peter.


Sent from my iPhone using Tapatalk Pro

[joeavaerage]

Hi Peter,
that spindle looks like the deal OK....and very competitively priced.

My own spindle is broadly very similar. It rated speed is 10,000rpm, so it has an S1 torque of 3.3Nm, which I think you'll agree is very useful. Despite being a 10,000rpm rated spindle its max is 40,000rpm.
So this spindle has quite a good low end but also a very useful top end. It has an HSK32 tool interface.

As I have no ATC tooling currently then going straight to HSK32 is no impediment, and especially if I want to use those high rpms is very desirable.

At the moment I’m rather committed to the TTS tooling system.

I'm not familiar with TTS? You have quite a committment to it and I can well imagine not wanting to change.

Is your spindle controller synchronous or something? That is to say if you bought another VFD would that run your existing spindle?

What is certainly true is that in the last two years, and particularly in the last year, the price for these types of spindles has come down dramatically, but they are still not free.

Craig

[phomann]

Hi Craig,

TTS tooling was popularised by Tormach.
The holders just have a short 3/4” shaft, 1.5” long. They are held in a R8 collet.
Some people complain that they can pull out under heavy load. But if it happens it’s most likely that they are being driven very hard. I haven’t seen it with my 750w spindle.

Cheers

Peter


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[peteeng]

Hi All - In another thread there has been debate over c column vs gantry style machines and various materials. I have made a comparison study to investigate this issue. Its a face off; raised moving column vs gantry. I made the main things the same size as close as possible. The C Mill weighs 1222kg and the gantry mill is 1305kg. Could get them closer but for now that's good enough. All parts are steel. The bearings are dummy geometry same size as a 30mm car. The Z axis is placed in the same relationship to the table in both models. The table is retrained and is 300mmx400mm. I expect with lightweighting it could come down to half these figures so maybe a target of 600kg. Obviously if you used aluminium it would be 70/200=0.35x the stiffness, if concrete say 50/200=0.25x the stiffness and if EG it would be 25/200=0.125x the stiffness and to complete the materials if cast iron it would be 100x200=0.5x the stiffness.

I made the two machines in the same model so its easier to compare. I used a linear mesh of 15mm to make it solve fast. I used 1000N at the Z axis end in each dirn. and the results are (envelope please)

X dirn C mill - 13.3um ie 75N/um Gantry mill 4.5um ie 222N/um
Y dirn C mill - 4.2um and gantry mill 3.8um
z dirn - C mill 9.6um and gantry mill 4.1um

Seems the gantry wins. The C frame footprint is 650mm wide by 800mm deep. The gantry is 800mm wide by 700mm deep. These can be tuned a bit... I just noticed the gantry machine is deeper then needed for the 300mm travel so reducing it by 100mm will bring the weight down top parity or better to the C machine... If you go the C then the arm or outreach needs to be bigger to improve its torsional stiffness (if needed) so its weight will climb... The gantry seems to be nicely balanced in all directions. I imagine I could make the C mill the same stiffness as the gantry by making the arm deeper and bigger... Next time around. Peter

[joeavaerage]

Hi peteeng,
good work.

I might try something similar but with a regular column.

What does surprise me is in fact how similar they are. If this were are far as the design goes then as you say the gantry wins out, but with more detailed design work they may get closer rather than further apart.

My proposal would be a fixed column, but would by necessarily be somewhat bigger dimensionally but the same weight overall as the 'rear wall column' version you have drawn.
The gain, if indeed there is a gain at all, is that the spindle nose does not have to extend downwards.

In any event I like this 'broad brush stroke' approach. You can see clearly why one arrangement is better or worse than another without getting bogged down in material details.

I'm thinking that I would probably ascribe a total and fixed volume of material, thus any design must be the same weight, but that material can be distributed in a fashion to do the best
for that style. In the case of a C column, then the column itself, followed by the headstock, whereas a high wall gantry design the gantry you would devote more mass to the gantry.

Craig

[peteeng]

Hi All - I've had a play with the column design. I made the arm 300mm high vs 250mm and this made the C frame a bit better. Although I feel with tweaking I could make the C frame same as the gantry design I can see the gantry has better support in the cross dirn and Z direction. Plus it creates a natural tub for a wet machine. I feel its possible to use any material to achieve a given stiffness given enough real estate. Its the required footprint that drives the ultimate size of the parts/machine and most people I think make their machine too big and the footprint too small to get really stiff machines.

I'm happy that two recent threads have come up with the EG being a very low modulus as I have found. I had hopes otherwise but E=20-25GPa although it will be very damp is not stiff enough for me. If I have to make moulds then I'd go carbon fibre and get 70-80GPa or laminated AL at 70GPa seems to be the productive path for me... or lam steel max E.

The only other approach is to go with exoskeleton type machines and they get complex fast.... Peter

On another note the specs came thru for the N23 flanged harmonic drives today and they look excellent. So now I can pick N23 or servos. The client for No1 Epoch has picked steppers (damn) but I think I'll go servos on lanky. Its time to up the anti.. Peter

[peteeng]

correction Ante not anti

[peteeng]

Hi All - I often sight a stiffness chart to people here. But I have not been able to find where I got that snip from. Today I was looking for an article and came across it by accident! In "Metal cutting theory and practice" see below. Now you can search for this in Google Books and have a good read. Peter

[joeavaerage]

Hi,
just received the oscillating pump from Auckland.

I was correct, the no back pressure flow rate is 1.4l per minute, not the 14 l per minute advertised.
The company whom supplied it supply the recreational vehicle market, they are not pump specialists. Disapointing ...but it is what it is.

Craig

[peteeng]

Hi All - I'm looking at the walls of the Mill.

Its distilled down to a high wall design. The way my routers work they require a 100mm wide land on the top of the wall to accommodate the rail and the drive. So if I cast a 500mm high 100mm wide wall in grout, how wide is the same stiffness wall in steel? Turns out to be 58mm. The steel wall weighs twice as much yet is the same stiffness. The concrete wall weighs 115kg/m and the steel 228kg/m. I think the E40 for the grout is conservative but will have to test. My other option is to make it in fibreglass which I can get 35GPa out of (proven by tensile, compressive and flexure tests) but then vacuum casting it will be a mission in one go or make it in parts and then adhere together. I have always been seeking the "pour into a mould solution" and the grout fulfils that...

Plus the grout is very damp. Plus I can cast the grout using ribs and further reduce the weight... This appears to be the path at present. Same for the base, cast and use a honeycomb or isogrid back... I will check an alum sandwich design before the final decision is made.... Peter

so I did the numbers and I won't bore you with the process - If I use 10mm al skins on 80mm plywood (100mm total) I get the same stiffness as the 100mm grout wall. It weighs 110kg/m so is same weight as concrete. Seems the concrete is the go as it can be optimised in shape... and no wastage in the process... I think I have been here before...

[joeavaerage]

Hi peteeng,
I follow your calculation but whom, in their right mind, would use a solid slab of steel 60mm thick? Were it a welded structure it could be made stiff and yet a lot lighter. Of course a welded structure
would require TSR.....a path we've been down before. As a direct solution for one off or low volume production then casting solid grout is probably the way to go. Only at scale production would steel start to look
attractive.

I'm just not sure that a comparison of solid steel verses solid grout is that useful because in practice steel would be a structure rather than solid.

That is not to say there are not components or parts that you would make out of solid steel........but many more steel parts that would be a structure of some kind.

Craig

[peteeng]

Hi Craig - The maths process gives insight to what is needed. A ribbed design will be less stiff then solid at the same width. It all comes down to the many variables each Maker has. The numbers indicate that I can make a mould and pour in a material to achieve the result. If I go welded steel I have to have parts made, weld them, TSR then machine. If I use grout I pour it into a mould get the shape I want. Then either 1) take the parts to my local stone mason and have him flatten the tops and drill the holes b) lap the tops myself which I have done in the past c) glue metal to the tops and take it to a machinist. Seems C) is the path for me at the moment. I can make the wall in any material and get to the required stiffness if width is not limited... By the way there are many thick castings in cast iron in big machines much thicker then 60mm... The other option is bolted assemblies and that's still on the books to compare to... I'll also say that people using standard hollow sections are in a trap. Sections have good global stiffness but poor local stiffness, machines need really good local stiffness at load transfer points and hollows fail in this respect all the time... Onward chasing that Grail, I saw its tail go around the shed corner...got to be quick. . Peter

to clarify something. If you make a frame for the wall then the transverse stiffness is different at different places along the wall. If you were making a precision machine this presents a problem in achieving accuracy along the wall. That's the reason for using a slab vs a frame. eg CMM's tend to use slabs vs frames for this reason...

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[joeavaerage]

Hi peteeng,
if you were to use a slab of steel I would use it as the base rather than the walls. You could then mill T slots in it, T slots are just so damned useful. You'd probably want at least 50mm, but maybe up
to 75mm if milling T slots into it. You really heed enough thickness so that the T slots do not render the base too gutless.

I had 16mm T slots cut into my X axis bed, that is 16mm at the base of the T, which just happens to be a perfect fit for an ISO 10mm nut across the flats. Thus I use 10mm shank bolts/screws with 16mm (F-F)
nuts. Not going to hold down the engine block of the Queen Mary, but still damned useful.

Craig

[peteeng]

Hi Craig - The issue with a large metal slab for the base is that no machinist in my area has a mill big enough to level it, and I don't have lifting gear to lift it. I say a lie actually because one of my ex employers 2 hrs away has a Russian mill with a 6m by 2m bed but they charge a ridiculous rate... even for "friends". I liked that machine because we would walk around on it discussing set ups and programming... But I may have the same issue with a crete bed...

So I ran the wall in GD and in form finding in Fusion., Both came to the conclusion that a single column across the void would do the trick. Since this "column" has to move as the car moves then it becomes a solid wall. The GD tends towards a slight I beam which makes sense.. Now I have moved up from 20mm rails to 30mm rails I'll have to review how wide the drive land needs to be as well.... Peter

0.050x1x1x7800= 390kg way past my hernia limit...
0.1x1x1x2300 = 230kg of crete still too heavy for me!

[peteeng]

Hi All - I usually use 100x10 or 100x12mm flat bar for the top of the wall. But using the 30mm rail means it does not fit with the 16mm ballscrew bits unless I make a custom nut mount or am I game to sneak 1mm clearance out of it? So next extrusion size up is 114mmx12mm which is OK. for now. Or I get a special part laser cut which is possible.. But I'll go with the 114mm for now. For those into thermal expansion crete vs aluminium I know! But I could use steel then it has to be zinc plated or painted.. I like aluminium...

mild steel 11-12 um/m/C
al 21-24 um/m/C
crete 13-14 um/m/C so delta is 12 so for a 1m length it changes 0.012mm per deg C so on a hot day 20C (40C summer 20C winter) maybe 0.2mm so I'll have to put in AC in my shed...Peter

I think I may machine 2mm off the std nut... 2mm is heaps of clearance

[joeavaerage]

Hi,
given that there is little happening at work on a Saturday I was able to turn the main isolator off and install a new three phase D curve circuit breaker and a three phase plus neutral socket with
which to run my new spindle. Runs very sweetly. After about an hour at 24000rpm the 8l coolant reservoir is up to about 22C from about 14C....so the spindle does produce some heat.
May need to look around for a heater core out of a car.

Craig

[peteeng]

Hi All - Epoch5 is maturing. I only have the rotary to integrate into the machine base and its ready to detail for manufacture. I have most of the structural parts in stock... Craig in the image with the column you can see that by adjusting the column (some may call it a riser) height it can be a std 3 axis or any height needed. For the 5 axis it needs to be 150mm high. So its a hybrid column/wall machine.... Peter