Show how to build a CNC machine from the very beginning to the end

[louieatienza]

Hi Sky......one question I just remembered, what are the diams of the mounting bolts in the base, as they will be used to screw in the lifting screws.....I think they were 8mm........4 of those with rings should be OK to attach a rope sling to for lifting.

I assume that rings with screws can be used with the mill in the cabinet attached to the bottom frame and allow a sling to be attached with shackles down each side of the column........I hope the balance is OK for the lift.

I just had a thought, if the screwed rings are not available, all you need is 4 pieces of 3mm thick steel plate 130mm long, bent into an L shape with holes at the ends.

You can then remove one mounting bolt at a time and push the bent end of the plate under the base and push the bolt through it, and a shackle at the other end for the rope sling.....now my engine crane can do the rest easily.

I'm paranoid about handling heavy weights, having had to do it in industry for over 50 years.
Ian.

You can easily get Kindorf or UniStrut "L"-brackets that would be more than adequate for the job and they're really cheap.

[Skyfire]

That BT30 looks very nice indeed. A BT/ISO 20 belt-driven spindle with 20k RPM would be VERY interesting! The bearings would have to handle cutting metal all day long. I bet a lot of DIY CNC people are looking for exactly that. Also motors/belts would be very nice to see as others have said.

Hi, on my opinion, spindles over 12k RPM should consider high speed spindle directly or at least shaft coupler driving type between spindle motor and spindle unit. Belts are not very good for so high speed spindles..

Yes. all spindles should be supposed to work all day long.. Temperature is the most killer of the spindles here... so make sure temperature rising controlled well is the key point here.

Thanks !~

[Skyfire]

I know hes got 12k, 20k i think is not viable. Not because of the bearings, but because the belt cannot take that high a linear speed. GT2 Timing belts are typically limited to about 6500 feet per mnute at the extreme, HTD are lower. V belts can be slightly more, but not much. this is why you don't see many belt spindles past 12-15k.

I think if he did 20k, he would need to make it direct drive and develop a creative drawbar.

edit: the outer extreme limit of a gt2 belt at 20000rpm would need a pully no larger than 1.24".

is that possible? im not sure it is.

Quite professinal explainations here..

[Skyfire]

Oh, and dont say "Antirust vaseline coated". Vaseline is associated with medical/etc here. say cosmoline, or just anti rust.

Oh. I wasn't aware of that.. LOL.. thanks I will correct this.

[Skyfire]

Same in IE.

cheers, Ian

My IE seems no problem.. Mine is IE7.

but will solve it any way.. maybe just leave enough blanks below the labels for simple solution.

[Skyfire]

Hi Sky......one question I just remembered, what are the diams of the mounting bolts in the base, as they will be used to screw in the lifting screws.....I think they were 8mm........4 of those with rings should be OK to attach a rope sling to for lifting.

I assume that rings with screws can be used with the mill in the cabinet attached to the bottom frame and allow a sling to be attached with shackles down each side of the column........I hope the balance is OK for the lift.

I just had a thought, if the screwed rings are not available, all you need is 4 pieces of 3mm thick steel plate 130mm long, bent into an L shape with holes at the ends.

You can then remove one mounting bolt at a time and push the bent end of the plate under the base and push the bolt through it, and a shackle at the other end for the rope sling.....now my engine crane can do the rest easily.

I'm paranoid about handling heavy weights, having had to do it in industry for over 50 years.
Ian.

Hi handle, I think you have thought all over the details that how to settle the SVM-0 in your home---I even think you can write a guide book now!

The cleaning works below the machine base may be the most difficult point here. I think your method will work well~ And I think air flow may helpful, but you need to control the flow not too strong to spray the swaf into motion parts...LOL A long brush like the one we used in chemical labs to wash the test tubes will be a helpful tool I think.


And the screws of the machine base is 10mm ones. I think I can include 4 ring scrws with every machine incase users can't find nearby.. I think we can make the string length adjusted before lifting to make sure the hanging point is very close to the center of gravity. It must be near to the column side.

[ihavenofish]

Hi, on my opinion, spindles over 12k RPM should consider high speed spindle directly or at least shaft coupler driving type between spindle motor and spindle unit. Belts are not very good for so high speed spindles..

Yes. all spindles should be supposed to work all day long.. Temperature is the most killer of the spindles here... so make sure temperature rising controlled well is the key point here.

Thanks !~

When i was talking to the people at the fancy spindle company that use water jackets, they explained it as:

You don't need water cooling to protect the spindle. It can run all day at max speed with no water. You need it to normalise the temperature so the dimensions and thus machine accuracy do not change.

BUT, when they talk about that, they mean the spindle growing .0002" over the course of an hour. It is something that we can happily "sacrifice" to keep the complexity down on a low cost machine. As you say, the temperature only rises 45C, which means the spindle grows less than 5 thou over its entire length from cold to max temperature. Warm up the spindle before cutting, and you'll likely never see an issue due to spindle heat.

[Skyfire]

When i was talking to the people at the fancy spindle company that use water jackets, they explained it as:

You don't need water cooling to protect the spindle. It can run all day at max speed with no water. You need it to normalise the temperature so the dimensions and thus machine accuracy do not change.

BUT, when they talk about that, they mean the spindle growing .0002" over the course of an hour. It is something that we can happily "sacrifice" to keep the complexity down on a low cost machine. As you say, the temperature only rises 45C, which means the spindle grows less than 5 thou over its entire length from cold to max temperature. Warm up the spindle before cutting, and you'll likely never see an issue due to spindle heat.

very good point here! I just want to say that you can have some good tools, but something same important is that you know how to make it work best!

[handlewanker]

Hi Sky, thanks for the complete solution to the lifting and the enclosure swarf removal, now I can devote my thoughts to the 4th axis design.

BTW, for the swarf handling I only use a brush to keep the immediate area on the table of my bigger mill clean, never compressed air, and I find a 50mm paint brush to be the best solution for swarf handling.......washed in kerosene frequently it never get oily and gunky, so I'll clean the area of the SVM table by hand and just clean the bottom out once a week.

I think the bigger SVM-1&2 mills with flood coolant would benefit from having a cleaning hose so that coolant can be used to flush the swarf away.....I've seen that mentioned on some other threads.

One sticky question I'd like to ask......what kind of warranty do the buyers get.....electronics being what they are, the smallest component can cause the biggest shut down etc.

I think there should be a circuit board replacement option within a warranty period if the problem can be identified or simply made available if out of warranty.

However "if" the components are easily identifiable (and a good clear circuit diagram of all the components and circuits) without dedicated IC's that can only be sourced and installed at the build time with a surface mount facility, then this would go a long way to ensure customer confidence and satisfaction.

There is a proverb that goes...."For wont of a nail the shoe was lost, for wont of a shoe the horse was lost, for wont of a horse the rider was lost...." etc etc.......and in the end the outcome was that the battle was lost because of a horse shoe missing a nail........one blown resistor or simple capacitor can ruin my day when the light goes out....LOL.

I don't think a handbook explaining how to use the mill is necessary or dire warnings not to hold the chuck when the machine is switched on etc, but pertinent information with regards to machine performance and tweaking which are relevant to the various options would be handy, but I think to cover all bases in one hit, a PDF manual down loaded from the website would probably be the simplest solution for all options down to the most obscure.

This way the problem of "Chinglish", which most if not all manuals supplied with Chinese machinery are prone to, can be cured right at the heart of the source......I think people on this forum would be glad to assist in the correction of any errors on an ongoing basis as has already been indicated.......all those who purchase the equipment are shareholders with vested interests anyway...LOL.
Ian.

[handlewanker]

When i was talking to the people at the fancy spindle company that use water jackets, they explained it as:

You don't need water cooling to protect the spindle. It can run all day at max speed with no water. You need it to normalise the temperature so the dimensions and thus machine accuracy do not change.

BUT, when they talk about that, they mean the spindle growing .0002" over the course of an hour. It is something that we can happily "sacrifice" to keep the complexity down on a low cost machine. As you say, the temperature only rises 45C, which means the spindle grows less than 5 thou over its entire length from cold to max temperature. Warm up the spindle before cutting, and you'll likely never see an issue due to spindle heat.

Hi, that's very interesting, if that spec applies to the water cooled spindle Skyfire is supplying as well, then water would not be necessary unless the work was so nitt pickingly critical.

I have read that a detected water leak can cause the spindle drive to shut down, and due to the cost of a rebuild would make it totally scrap whereas it's perfectly functional without the water......as long as water was not used in the beginning.

I wonder if transformer oil could be used as a cooling medium for the spindle....it's used to keep large power handling transformers cool and they really need it.

Even if the oil leaked out continuously the system would not short out and no real heat is generated anyway.

I would think that if the housing for the High speed spindle was filled with transformer oil and capped off, with a thermometer used to monitor the inside temperature, that would indicate if a real need for a continuous flow was needed.

This would cut down on the trail of piping and/or wiring to the high speed head when it's fitted, and also make the water pump and it's transformer power supply obsolete,

Some of those hobby routers on EBAY with the water cooled spindles have really large bore piping and would probably give large flow rates, all for nothing apparently.

If Skyfire sanctions it, I will run my high speed spindle dry as a bone or maybe filled with oil, whatever.

I've also heard that in cold weather the system has to be drained of water to prevent it from freezing, and also an anti freeze compound with corrosion inhibitor used to prevent corrosion...... oil would not have that problem, but it would have to be cold enough to freeze the nuts off of a brass monkey to worry about freezing oil.

I have a feeling that with the spindle casing cooling system filled with liquid, this may cut down some of the noise audio wise too.
Ian.

[handlewanker]

Oops....double post.

[ihavenofish]

No, for the water cooled motor spindles, the water is mandatory to get any amount of power out of them. If you tried to run with no water, you'd probably not get more than 30-40% of the power before hitting the thermal limit.

My post was specifically about belt spindles, where the heat is from bearing friction.

[handlewanker]

Hi, does that mean you can't use transformer oil to cool a water cooled spindle?

You would not have any corrosion or freezing problems with oil cooling, and I doubt that the water coming out of a water cooled spindle is near boiling point, so why not oil?
Ian.

[LeeWay]

Unless it is some kind of special synthetic cooling oil or solvent, wouldn't it need a pumping system too?

I know some high performance engines have a separate oil cooler because it gets hot and stays that way. The radiator system isn't enough to keep the engine oil cooled by itself.

Granted, I don't know a thing about transformer coolant, but I do have one on my property.

In a closed spindle system, I would think any kind of oil would be the wrong stuff. It keeps and holds heat unless actively cooled by an outside system.

[handlewanker]

Hi Lee, that would apply to a water cooled system too....once water gets to 100 deg C it boils, but it does not lose heat just circulating round the system without a heat exchanger, IE a radiator.

I would think that if you put X amount of heat into a water system or the same amount into an oil system you can also take the same out with a heat exchanger.

This is important, because if this is true for oil or water systems, I'd use oil every time.....no corrosion, evaporation or freezing and no need to keep the corrosion inhibitor up.

I can't think of any other draw backs.....water is cheap, but oil is not all that dear.
Ian.

[ihavenofish]

You need a circulating system with a reservoir and radiator. Distilled water is most commonly used. Deionised water would be more ideal, but harder too get. Deionised water isn't conductive. Using oil would not be ideal for the pumping system, too viscous. I think if not mistaken, these chines water cooled spindles are designed for straight distilled water, and wont corrode. If corrosion Is a worry from an accidental leak, then you'll need a proper refrigerant fluid.

Transformer oil is designed to be in a static bath to transfer heat to the outer shell of the transformer, because air alone is a very poor conductor. It is the equivalent of putting thermal paste on your computer CPU heat sink. If your idea is to just fill the spindle with oil and leave it... no. Definitely not going to work. The volume of oil inside the spindle is minimal and would do nothing at all if not circulated to a heat exchanger.

If you are worried about finding a system, it's easy. Find a nice quality computer water cooling system designed to handle 200+ watts of dissipation. That should handle the spindle easily, and not cost much more than $100. All you need to do then is find the correct hose fittings to go from the radiator, to hoses that fit the spindle. PC cooling blocks tend to have very large hoses.

Here is an example:

[ihavenofish]

Oh, they do make air cooled versions of the 80mm spindles.
2 2KW Air Cooled Cooling Spindle Motor CNC Router | eBay
they also have the side effect of blowing chips out of the way which can be nice.

The drawback to these is a lot more noise. A LOT more noise. Like 100 decibels of noise.



Did I mention they were noisy?

[ihavenofish]

Here is a useful tool holder design for the ISO20 (and bt30 for that matter). It is an ER chuck, but sunken into the holder. This gives you maximum clearance, but also more rigidity in cutting. You can fit an ER16 collet into the ISO20, holding up to a 3/8" tool.

[handlewanker]

Hi avno, I mentioned the oil because the previous post said the water cooled spindles do not need water as it's just to get maximum accuracy, whereas that is not true, they do need continuous water cooling as they're designed to work that way.

That water pump and radiator for the CPU, provided it can shift the heat build up quick enough seems like an ideal solution.

I don't know if Skyfire supplies any cooling capability with the water cooled high speed spindle I have as an option with the SVM-0 mill I am purchasing, but I think a pond pump was in the picture....no mention of a radiator etc, but that is a small worry.

Transformer oil is non conductive to electricity, and I thought that if it was used it would not make a spindle scrap if or when you get a cooling liquid leak detection, if the oil did leak out.

As far as I know, and I may be wrong, the prime reason that the transformers are filled with oil is to prevent any moisture penetrating the windings and causing a short.....cooling is not the reason, although some cooling does occur with the design of the casing.

This is so with a welding transformer that is oilfilled......no cooling radiator or pump needed and no cooling fins on the outer casing to ensure cooling.
Ian.

[handlewanker]

Here is a useful tool holder design for the ISO20 (and bt30 for that matter). It is an ER chuck, but sunken into the holder. This gives you maximum clearance, but also more rigidity in cutting. You can fit an ER16 collet into the ISO20, holding up to a 3/8" tool.

Hi, I have an ISO20 spindle option with a supply of ISO20 tool holders with ER32 chucks on the end.....$38 each.

This will give me a 20mm tool capacity, which the ISO20 shank can well handle.......if the R8 can, so can the ISO20 even more so.
Ian.