I am doing vibes in a food service facility, that is full of stainless and aluminum motors and gearboxes. The problem I have is of course getting a magnet to stick to most of the equipment. Holding it on does not do well with any high freq (spike energy or regular g's)
I believe I am going to go with a 2" stinger, but am concerned with the gearboxes.

1.) Is anyone else doing these kind of units, and if so, how do you get good data.?

2.) If you're using a stinger, does it have a sharp tip, or flat?

Dave

Dave,

I too work at a food plant and have the same situations you have. Use a 400 series stainless steel button and glue, screw, or weld them in place if possible. The frequency response of a stinger is limited and won’t always provide an honest severity of the problem. Paint used to mark your spot for repeatability always gets washed away as well. There is a lot of information relative to the frequency response of different types of mounting applications. Stingers rate at the bottom.

LocTite Depend 330 adhesive for locations not directly in the path of a 1500 psi cleanup hose and gun works great. It seems like it becomes a challenge to see how long it will take to blow them off finisher and mill bearings. Screwing them on is time consuming but worth the effort. That monitored point is always there without worry of the accel being placed in the wrong spot if data is collected by someone else. Same for welding.

Hope this helps you!

Dave,

You can get cheap magnetic stainless targets fro spintelligent labs. $60/100. 1 1/4" dia x .040 thick 410 stainless I think.

Has anyone heard from Spintelligent? Seems someone was out several thousands $ when John went AWOL.

Dave

Dave,

Eric Thompson at Spintelligent e-mailed me in Nov, 2007 and said they were still in business but had been going through some changes.
try him at eric@spintelligentlabs.com

If that doesn't work, e-mail me. I have some other ways of getting in touch with him.

I've been trying to buy those 'targets' from Eric, but have not gotten a response in the past couple of months.

I use the 2" stinger.... a lot... most of the time actually. High frequency response is fine if you use a good bit of pressure. But you have to brace your hand or elbow or arm against something... you can't use it like we used to try and use the IRD 544 velocity pickup with the 9" aluminum stinger. What you will see on severe defects is an "amplification" of the high frequency vibration, which is not necessarily a bad thing (comparison spectra or waveform plots look more urgent). But when a defect is that bad, I'm not too concerned with amplitude accuracy.... it needs to be replaced.

That said, I am in the process of putting targets on my most critical machines, because you will get better, more repeatable data... no argument there. Also, using a stinger is harder on you physically, especially when you hit 50 or so.

Using a stinger is faster and cheaper. As someone noted recently, putting targets on 10,000 points is expensive and time consuming, and usually not necessary. Besides, what does everyone do on the 50% (or so) of all points where you cannot put a target, even if you want to?

Stud mounted is best. A flat magnet on a flat, paint-free surface is next. Targets with high-strength flat magnets follows. A good, 2-rail magnet on a smooth, paint-free surface (flat or rounded) is 4th best. Finally, I think a 2" steel stinger, properly held and used, is better than a 2-rail magnet used on dirty, unprepared surfaces which I have seen a lot of folks do.

I'd use the stinger where you can. I'd glue on magnetic stainless targets where you need more accuracy (expensive or critical machines).

Dave,

If you have access to an onsite machine shop with at least a lathe, ordering the bar stock and parting them off your self will save tons of money. I make mine 5/16” to 3/8 “ so I can drill and tap or counter sink the ones I want to screw down and do nothing to those I intend on gluing or welding in place. Most parting tools and a decent set up will leave a good enough finish for a magnet to bond to very well.

I don't have a problem making the discs, as I have made them before. But that was when I was a supervisor for the company, and was supervising the data collectors.
I now do the data collection myself, for myself, under contract to different companies.
The time and expense involved will not be reimbursed by this company.
I'm doing the stinger thing I guess. I have a 2" steel one. Guess I'd better shine it up.

Dave

Dave,
I took one of my 3/8" thick by 3/4" diameter measurement point disks (Magnetic Stainless) and had a conical point machined on one side. Whenever I encouter a nonmagnetic machine surface, I slip the pointed disk over the flat magnet on the accelerometer. This method is very quick, convenient and gives better frequency response than a long stinger.

Walt

Hot daggone Walt
I like that idea.
I'm going to try it since the stainless and aluminum is not on every piece of equipment.

Thanks

Dave

quote:

Originally posted by Walt Strong:
Dave,
I took one of my 3/8" thick by 3/4" diameter measurement point disks (Magnetic Stainless) and had a conical point machined on one side. Whenever I encouter a nonmagnetic machine surface, I slip the pointed disk over the flat magnet on the accelerometer. This method is very quick, convenient and gives better frequency response than a long stinger.

Walt

Walt - Can you post a picture of your disk?

Steve,

Attached are photos of the short stinger and longer (4") stinger that can be attached to an acceleroemter with a flat magnet base. The short one can be kept with pocket change until it is needed.


Walt

Acceleroemter_Stingers.pdf (304 Kb, 44 downloads) Photos of accel stingers

Walt, is that 4" stinger just stuck to the flat magnet? I'm a 'stinger' guy, but I would never have imagined using that setup.

But your low profile, fat stinger is an interesting idea.

I like the idea of the magnetic disk stinger type thingy.

Just expanding on this for a moment. If a larger diameter flat disk was carried as well, could this be a quick and easy method of taking readings across motor fins, especially the wider ones?

Big AL,

I'll let you know, because that's what I'm going to try. I'm going to make two, one about 1", and one about 1-1/2" for motors with the wide fins.

D

Rusty,

The 4" long stinger is from PCB and has a 10-32 tapped hole. The 3/4" diameter glue disk is also from PCB and has a tapped 10-32 hole. The three pieces screw together with 10-32 stud without machining.

The shorter the stinger; the better the flat frequency response. You can't beat the 3/8" long stinger. It is also very stable to hold. It works very well with the side exit accelerometer to reach into tight axial measurement points. Sometimes small size does matter!

Big Al,

Sure you can use a larger magnetic disk or rectangular bar to bridge motor cooling fins with a flat magnet acceleroemter. If you were really fancy you could machine three raised flats on the base of the disk at 120-degree spacing. This would allow for 3-point contact (2 on one fin and 1 on the ajacent fin) to avoid the "rocking" contact problem.

My other jewel is a disk with a machined groove that I use with flat magnet on accelerometer when I need a quick measurement on small pipes or tubing.

Think outside the accelerometer!

Walt

Very, very interesting.... opens the door to all kinds of possibilities.

Walt
On the machines were you have to use the stinger setup do you put an indent in the equipmnet so it will not slide around and you are at the same spot every time?

Lee

Lee,

I do very little routine walk-around programs; mostly diagnostics. A spring loaded prick punch or even a drill point can be used to enhance using a stinger. Most machines I work on are so fouled that either the detent hole gets filled or completely covered. I don't think it is worthwhile, but it may be useful for food production or other clean and nonmagnetic machines. Maybe "stinger man" Rusty can provide some insight!

Walt

I use the stinger for most "run of the mill" equipment, but not on critical gearboxes or compressors (Centacs). I use the large Starrett automatic center punch for marking most of my locations (don't bother with the smaller ones, or the cheapies... get the big Starrett). My cable has a mil spec right-angle connector so I am able to get a good bit of pressure on the accel. And I seldom hold the accel "free hand"... I always have my hand, forearm, elbow, etc. braced solidly against something. I rarely have any ski slope and it's easy enough to just retake the data if I do. But it's pretty hard on you physically to take data using a stinger (if you're doing it right). By that, I mean hard on your muscles and joints. People think I lift weights, but it's just pressing on that stinger thousands of times each month, for the past 13 years.

I followed another analyst one day duplicating part of his route. He was using a typical 2-rail magnet on unprepared surfaces. I had a lot better high frequency response than he did on most all points.

Stingers have gotten a bad reputation, I think mostly based on tests done 30 years ago using the 9" aluminum stinger that IRD used to ship with their old analyzers. Of course, if you have a lot of high frequency noise, you are probably going to excite the resonance of the stinger which may give you a nastier looking spectrum. But that may not always be a bad thing if you are trying to convince someone to take action on an obvious problem.