Lost a vacuum motor.

[gundog]

I lost one of my vacuum motors for my hold down system. The number on the motor is 117123-00 I do not see that number listed anymore with Lighthouse (I found it I searched the wrong number)the motor was made by Lamb. I will call Lighthouse tomorrow. I am not sure what is wrong with it. When it first starts it runs for about 10 seconds then it makes a funny noise and loses about half of its vacuum pressure.

I looked at the armature and it looked a little dark so I spun the motor with a socket and impact gun and ran armature chalk on it and cleaned it up. I have not tried it again because it is a pain to change and silicone it I want to know it is fixed before re-installing it. I don't think I fixed it I am going to take it to an electric motor shop and have them test it.

Do they make better motors than the Lamb? I don't really have that many hours on it for it to be bad. The motor has always run in the open for cooling and in parallel with another exact motor. I just redid the vacuum system so I can now run one motor at a time so for now I will just run on one motor until I get this fixed.

If I replace one motor will I need to replace them both? I am wondering if a new motor ran with an old one or a different brand will cause an issue.

Thanks Mike

[Gary Campbell]

Mike...
Lighthouse should have the Ametek (Lamb) 117123 and their own US made replacement. They are shown on the website in 2 diffrent sections.

The Lighthouse brand are the ones I have been using. I am ready to order 4 more for another system. That part number is LH 7123-xx. They also have brushes in case yours are worn or hung.

These motors only have a 500 hr life expectancy, but most of us that keep them cool have seen them live much longer than that.

[gundog]

Thanks Gary mine should have much less than 500 hours. Is there a way to see how many hours your Shopbot has on it. I only run my bot every couple weeks for maybe 4-6 hours.

Mike

[Gary Campbell]

Mike...
Many of thse motors have a warrantee. Give Ward a call and see if yours qualify.

[beacon14]

Let's see, 4-6 hours every 2 weeks, that's 2-3 hours per week, or 100 to 150 hours per year, you joined the forum 3 years ago, so 300-450 approximate total hours?

500 hours is the average life expectancy, that means half of them fail before that, right? Seems like you've gotten whacked by the law of averages.

[Gary Campbell]

Mike....
There is a hour meter gadget floating around somewhere, but I am not sure where. Maybe ShopBot Labs.... yep found it: http://www.shopbottools.com/LabFiles/odometer.htm

David....
I usually use mine 499 hrs and then sell them. :D

[gundog]

Let's see, 4-6 hours every 2 weeks, that's 2-3 hours per week, or 100 to 150 hours per year, you joined the forum 3 years ago, so 300-450 approximate total hours?

500 hours is the average life expectancy, that means half of them fail before that, right? Seems like you've gotten whacked by the law of averages.

I meant to say 4-6 hours every 5-6 weeks & I did not put a vacuum table on for the first year. I used to screw everything down with sheet rock type screws boy I don't miss those days. Maybe I just got a bum motor the other one works fine at least for now. If I were to guess how many hours I have on these motors it would be closer to 200 hours or less.

I just looked up an old post from when I originally built the table and put the vacuum motors in service it was May of 09 so I think my estimate is probably close.

Mike

[Brady Watson]

Are they being run unfiltered?

-B

[gundog]

Are they being run unfiltered?

-B

Yes. Do you think that is an issue? I do not cut very much wood or MDF only when I am making the table. I cut plastic and it does not create much dust. Edit: I talked to the guy at Lighthouse and he said as long as I am pulling air through a spoil board I don't need a filter.

When I pulled that motor the armature was dirty and I cleaned it with armature chalk (chalk is left over from my days as a Electric Forklift Tech years ago). I may just plug it in and see if that fixed it the brushes do not show much wear and the bearings feel good and it spins free. The funny noise was not like a bearing noise it sounded more like an electrical issue as it slowed and speed up then fell to a slower speed. I know it is not in the wiring I have checked that and proven it good with the other motor.

I am going to try it again with the cleaned armature and get back to you. After talking to him it sounds like the problem is a lack of air to the motors. By machining plastic there is not enough air leaking by to cool the motors. When all the valves are shut on the new system I pull 8" of vacuum measured with an automotive gauge for all intents and purposes I consider that perfect vacuum I pull 8" with one or 2 motors running because they are in parallel. When I was running them the other day in parallel using half the table I was pulling 7.5" and not flowing much air for the 2 motors. Both motors were fighting for the small amount of air pulling through the .75" Trupan spoilboard. I had been running them for about 3 hours when my vacuum dropped to 5" and one motor was making a funny noise. At the time of the problem I had no way of running just one motor the way they were plumbed & wired.

I have since re-wired and re-plumbed the vacuum motors so I can run one at a time or both if need be. I put in a valve for each motor and a switch to control them separately. One motor ran fine but the other made that same noise as before and that is where I am right now. I am going to re-install the motor after cleaning the armature and see what happens I will report back.

Mike

[Brady Watson]

Filtration plays a role in the longevity of those things. Yes - you do get some more performance out of them without a filter - BUT my feeling is, like yourself enough to not screw yourself later on down the line when you are in the middle of a job that has to get out the door on time. Even though your plenum may be sealed...I guarantee that small particles sneak by from time to time and this builds up in the housing. Tolerances get eaten up, and it sucks more power to do the same work...and power = heat, which equals death...as in burnt windings. Plus, Ward has recommended a small bypass hole on most of these motors to assist in cooling. I believe it was 'mandatory' or warranty would be void. (This is relatively recent, check to be sure).

All of these vacuum motors (starting with the 9-15 project) are band aids so people with little money can 'play too'. They really are not up to the task of day in, day out production machining. The 'Big Idea' was to buy & implement these cheaper vacs and re-invest the money you made with your new-found capabilities into a real vacuum pump...I think some of you are well aware of this, and have crunched numbers to compare/amortize. Still, some expect it to last forever. (No Mike, I don't think you are in that group.)

-B

[gundog]

Here are my conclusions. The one motor is fried I believe the cause was do to overheating caused by lack of air moving through it. This is what I learned my quest to create a highly sealed table created an issue by not allowing enough air to flow through the motors.

After talking to Ward @ Lighthouse he recommends a 1/4" hole to be drilled to make sure there is enough air flow to cool the motors the hole would need to be filtered. I do not like the idea of just drilling a hole so when I am not using all the zones I will just crack a valve open on a non used zone and watch my vacuum gauge to keep proper vacuum and allow enough air to flow by the motors. I played with it a little and it is pretty easy to adjust that way. I may add a bleeder valve that will allow me to adjust the amount of air to bypass.

After running these motors for 2 years I know they survive well when pulling 5" so if I am pulling more vacuum than that I will open a valve to keep it there. You can hear the change in pitch of the motors right at that level.
Mike

[Gary Campbell]

Mike...
I have a slightly different take on this. I have no plans to upgrade to a regen or other large vac pump in the future. I look at these parallel vac motor setups as a more than adequate setup for a small shop that doesnt have 3 phase power. Thanks again Brady for all the time, testing, and most of all for starting the thread.

That said, I do know I use them long and hard and most likely beyond their intended use. Even tho I have never had a failure, I expect it will happen. Replacing a motor or two a year is a small price to pay for this level of performance. Due to use of MDF (not ULDF) required when using a vac pump north of 10inHg, and the resulting loss due to that denser material, many shops with these setups cant hold the parts that we can. I give credit for this to the massive CFM that 4 of these motors develop.


I am going to get clarification from Ward on the "vent" requirements. Dont question the need, but according to the LH7123 data, a 1/4" orifice would flow 9.3 CFM and develop 9.33 inHg. To me that could mean that anytime these motors are pulling less than 9inHg, they are breathing enough to cool the rotor.(must be adjusted for altitude) I can pull 9 inHg with the valves closed (1400' elev), but seldom see over 8.4 with a sheet on the spoilboard. Your setup, and /or a very well masked zone could result in a better seal, and therefore less flow.

A small bleeder or even a relief valve may be the answer

[Brady Watson]

If you wanted to get nuts, you could wrap copper or AL tubing around the vac housing and circulate & cool it with a computer cooler or small radiator...It's not all that outlandish, if you lose just enough vac to fail with the cooling bleeder.

-B

[gundog]

If you wanted to get nuts, you could wrap copper or AL tubing around the vac housing and circulate & cool it with a computer cooler or small radiator...It's not all that outlandish, if you lose just enough vac to fail with the cooling bleeder.

-B

I had the same thought about making a cooling radiator.

Mike

[Gary Campbell]

Mike...
These vac motors have 4 distinct air paths. Vacuum inlet from the table, vacuum exhaust. Cooling air intake to the top (or bottom if mounted upside down) and cooling exhaust which is discharged radially from the midsection.

If these airstreams are kept separate and particular attention is paid to make sure that none of the heated exhaust(both) air gets near the cooling intake, the motors run pretty cool. Mine run cooler in the box than they did inverted under my table in a free air environment. My test was after 3 hours of pulling 8 inHg holding down a landscape carving.