Posts Tagged ‘cooling’

The full article on the Taig 24,000 RPM water cooled spindle conversion is now available on The Hobbyist Machine Shop website. Follow this URL: 

https://thehobbyistmachineshop.com/cms/projects/high-speed-spindle-for-the-taig-micro-mill

The new spindle performance exceeds all expectations. It is not a low cost option / addition to an already  adequate micro-machine tool system, but it does provide a very good way to achieve more than double the stock Taig spindle speeds.

Some applications using very small diameter tooling are performed much better when running adequate SFM and cut travel speeds. High speed spindles and especially water cooled ones like this example are a joy to use because of their extremely quite operation.

The Taig spindle is known for its quiet operation and the water cooled spindle here is in my opinion just as quite or perhaps more so, even running at full speed. Tool cutting sound is the same but the spindle motor has none of the sound of a high speed router.

The water cooling has been added to the high speed spindle through the red tubes in the picture. This is phase one where I will be using a reservoir with a sump pump behind the bench.. This should let me operate for maybe an hour or so. I don’t have any idea how much and how fast the water will warm.

The next step in the water cooling will be to add a closed loop system with a radiator to move the heat out into the ambient air rather than store it in the water tank. But first I need to determine through running and testing how much heat per hour is produced by the spindle in my type of operation.

I will be in the 10K to 24K speed range for many hours of continuous wax milling. I suspect spindle loads will be very low but only through running and testing can I design an adequate cooling radiator system.

Next is the spindle three phase wiring and power connection, followed by programming the VFD. If all goes well the spindle should be operational in a few more days.

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I operate three PC type computers in my workshop and each controls a separate CNC machine. I have two Taig CNC mills and a home brew (HB2) CNC gantry router. Two of the computers are refurbished., small form factor size. I paid no more than $100 for each of them. One is an HP Compaq and the other is labeled a Compaq. Their styles are different. The third is very similar but larger bare bones built up. Probably $250 invested in it.

None of them have great internal cooling as they were designed to operate in conditioned spaces. My shop operates at outdoor temperature. It’s been running 95 degrees in there for the last two weeks. Outside it has been very near 100.

The larger case unit running the HB2 has stopped suddenly twice in the middle of a long run. It ruined one piece and almost ruined the re-run second.  It is not going to be put back into service again in this hot weather.

The HP-Compaq computer is a sweet little machine, or at least it was. I just let it upgrade from Windows 7 pro to Windows 10. I use it with a smooth stepper so I don’t have to be concerned about pulse timing. The upgrade took many hours of loading and saving files. It converted just fine and MACH3 and the Smooth Stepper were performing well with Win10.

HP-Compaq

HP-Compaq

I left it on for a day with it doing nothing but staying on the network. I wanted to see if WIN 10 was going to do any self-updating since the install. When I came back to it the computer was dead. There is a single blinking LED on the motherboard constantly flashing at about 1 Hz with a slight audible click.

I did a lot of investigation and it appears the Power Supply has become nearly powerless. It is making 5 volts and something around 4 volts but there is nothing higher. It could be the shop heat was too much for it. None of the internal fans will run and it doesn’t even think about doing a boot.

I ordered another refurbished $100 computer (not the same brand, it’s a micro format Dell desktop.) because at that price I probably can’t even purchase repair parts. It comes with Win 10 installed, a keyboard and a mouse. Perfect system for CNC control.

Power Supply

Power Supply

Actually, I did find a rebuilt PS online for $25.00 free shipping from a company called Server Supply. So maybe I can get the little PC back into operation. BTW a new PS was $136.00 dollars.

So it looks like CNCing will be off line until I get a cooler day, like 80 degrees. My next shop if I ever get one will be air conditioned! Ha!

I just ordered a couple (2) 6-18 Volt Johnson 9167AK electric motors for the Roboboat project. I do not yet know if they are suitable. I’ll discover that once I receive them. This is part of the problem when buying something you can’t first touch and feel. Especially if it something you have never owned in the past.

The specifications seem to be OK and the cost was very low (about $7.00 each on eBay) so I figured it was worth the risk. That is all part of the cost when creating a prototype. If anything the motor’s physical size is what has me concerned. They just don’t seem to be big enough for the power they can handle. That is about 49 watts each. They weigh in at .45 pounds each so they seem to have some mass.

Johnson makes or sells a huge variety of small DC motors. These motors I picked are not the highest RPM but do have a lot of torque for their size. I also have to pay attention to the power they use as I don’t want to haul around large expensive batteries. I then also have to stay within the ratings for my speed controllers.

The reason I am posting this here is that part of my plan is to design and build (machine)suitable aluminium motor mounts for these (or any) electric motor I choose. High power also equals high heat so I need to design for the heat these motors are sure to produce. Of course I don’t expect to be running the motors at full power. (I could be wrong.) A lot will depend on prop size and pitch. Lots of variables.

The roboboat project is not intended to produce a high powered fast competition model boat. I am expecting scale like operation. At 1/16 the size of the original, the scale speed will also be 1/16. If the prototype ran at 48 MPH then the model only needs to run at 3 MPH actual to cover the scale distance. That’s a little less than walking speed. I am assuming the model will actually be able to run much faster than that.

 

Well maybe not my mind but just about everything else in the shop. The Texas heat spell got to me and I finally splurged for a new fan. I had a cheap house type fan for many years (plastic construction). You may see it in some old shop photos. It gave up at the end of the last heat season. This new fan is all metal and much more powerful. Note the description (in the store link) of the fan clearly states “High Velocity”.

I purchased it from Northern Tool and Supply for $89.99. With Texas tax the total was $97.41. I had it shipped to the local store for free (they didn’t stock them)  so for less than $100 it is a good deal in my opinion. Here is a link for everything you might want to know about this fan: FAN LINK

A workshop minded coworker (at my real job) and I discussed the merits of high velocity fan size for garage size shops. We were first attracted to the 30 inch fans but when I did the math (the engineer in both of us) of how much air at 8000 CFM those fans could be moving, the small 2 car garage would have served as a wind tunnel flight testing facility. 20x30x10/8000 = 0.75, a complete shop air change every 45 seconds!  The purchased 20 inch fan is still able to deliver nearly 6000 CFM on high speed. My testing so far shows the lowest setting very adequate in my shop.

There is no escape from air noise when moving that much CFM with a small fan at high velocity. So yes, there is some fan noise with this fan. It goes with the work and is definitely a function of velocity. The safety grill contributes too, but is a “must have” for safety sake. The sound level is very moderate and certainly is not a conversation stopper in a work shop. But in my home I would like it quieter, but then I probably wouldn’t want to be moving 6000 CFM of air. In other words, the sound is not an issue in the shop. A much larger fan turning slower, such as a Big Ass ceiling fan for example is quite, but you won’t buy one for $100.00. I also do not want to devote the space to a larger floor fan.

A breeze can be felt anywhere in the shop when the fan is pointing there. Spanning 20-30 feet is no problem. So the fan and the mild sound is not right in my face when working at the bench or machine tool. In fact if it were too close, it would blow the small parts right off the bench. Slow speed with the fan well away from the work area is my plan for operation. It is really a relief to have that air flow around me even if it is nearly 95-100 degrees in the shop.

The warranty from Northern say 1 year M&L. The warranty card in the box says three years. Printed ON the box it says 3 years. The first year is full coverage and the last two there is a $25 flat rate repair or replacement warranty period.

Most of us off my age have heard oscillating fans and their familiar “rumble” as they move back and forth. This is due to wear in the fan motor shaft bearings. The oscillation imparts a lot of stress into the shaft bearings due to the gyroscopic precession loads from moving the spinning fan back and forth. (Technical mumbo-jumbo, some of you may not understand, ha!) The same thing happens to fan bearings in moving vehicles. (It’s also why gyroscopes wear out) In any case I suspect the fan may get that rumble in a few years, but for $100 in this day’s money, I’ll have gotten my money’s worth. If it runs, I’d still use it with the rumble…

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