Any turners here that have a pacemaker?

[Kevin W Johnson]

A fellow member of our local turning club recently had to have a pacemaker installed. He was at tonights meeting and commented that he can't currently turn due to potential frequency interference from his 3520b lathe. Has anyone here had to make modifications (shielding, relocation of electronics, etc.) to overcome this? If so, could you share the mods that you made? I'd like to help get him back to turning.

Thanks.
Kevin

[Dan Hintz]

I don't have one, but if he wraps the entire motor casing, VFD, etc. (essentially the entire headstock) in a fine wire mesh and grounds it, there's no radiation to escape.

[Don Emmerling]

I have had a pacemaker/defibrillator since 2003 and have been turning using a Jet 1642 and Powermatic without any problems. I am not sure where he got that information but my cardiologist did not think that it would be a problem. You would have to put your chest right up against the motor to even begin to get a warning from the pacemaker that there was interference. There was a complete discussion of pacemakers and woodturning over on the AAW site just a few weeks ago.

Don

[Roger Chandler]

My wife is a registered nurse with many years of ICU/CCU experience and now for the last 6 years works for a cardiology group as a cardiac device nurse...............

She says relative to this, that it depends on the person and their circumstances. If a person is pacemaker dependent........meaning that their heart is not doing the pacing on its own, such as a person who has had an oblation done for atrial fib, or some other reason the heart does not properly send the electric signals correctly then that is when the problem arises.

If a person has a difibrilator {ICD} then they could get a shock if the interference triggers the unit..........that is like getting the paddles put to you and shocked...........it could cause you to fall into the spinning lathe or some other dangerous scenario..................If one actually ignored the first shock, then the second would be stronger and so forth..........not a good thing unless your heart really needs it...........it can only take so many of these!

The electro-magnetic field put off by a motor in close proximity to the pacemaker will cause interference........when a pacemaker is checked or reprogrammed by the doctor/nurse, they put a magnet over it to turn it off.

Finding a way to to shield the headstock might work, however until a person understands why they have a pacemaker/ defibrilator, then they should make sure they ask the company who makes their device..........each company.........Medtronic, St. Jude Medical or Guidant [Boston Scientific] has the parameters of each individual unit and can tell you if your unit is safe. They all have serial numbers and model numbers and each patient gets a card to carry with them that has their info on it, for reference purposes.

Make the call...........

[Dan Hintz]

The electro-magnetic field put off by a motor in close proximity to the pacemaker will cause interference........when a pacemaker is checked or reprogrammed by the doctor/nurse, they put a magnet over it to turn it off.
Just as clarification... doctors use an electromagnet to program the pacemakers/defibrillators because it provides a non-contact method of communications with the device (i.e., they don't have to dig into the skin or thrust a probe into the device). Getting close to the magnetic field of a stationary motor should not cause issues (we're not talking the field strengths used in medical scanners), it's the high-frequency EMF from the VFD controlling the motor (and the amplified version seen around the moving motor) that's the potential problem. If you're close enough, there's the potential for induced current in the device from the strong external fields... but man, that would have to be a strong field and you gotta be close. I do not have values to compare, but I would imagine an airport scanner has a stronger field than a typical home-based VFD-controlled lathe.

I doubt it would be an issue, but if you're concerned, wrapping the headstock in a grounded mesh will dampen all of the field (except what leaks out through the power cord, which will be completely insignificant).

[Roger Chandler]

Dan,

Is there a way to measure the field from your lathe motor......some meter perhaps? That way one could actually take that measurement and make the call to the manufacturer and get a definitive answer from them about the unit in the actual patient.

I do know that at airports, the scanners create issues as you suggest........one has to go through a pat down and not the scanner if they have a pacemaker/ICD.

[Dan Hintz]

They do make simple EMF meters for <$100, but they don't tell you much. A better tool would be a frequency analyzer with an appropriate antenna attached, but the cost climbs dramatically. For example, I have an FA built in the late-70s / early-80s that's good up to a couple of GHz in frequency... I bet that thing cost $10k back then (got it and two others for $20 each in an equipment clearing sale at a company I used to work for :D).

FCC Part 15 specifies maximum radiative power at the various frequencies, and the VFDs would have to undergo testing to be sold in the US. As an "unintentional radiator", I don't know if they classify the VFDs as Class A (commercial) or B (residential, the more strict of the two). Even though they sell to home hobbyists, lathes are generally considered commercial/industrial devices and the VFD may likely be labeled as Class A (someone will need to look to be sure... should be on a label on the VFD). If it is class B, the pacemaker manufacturer should be able to tell you if a Class B unintentional radiator will cause problems... if they say 'no', you're good to go.

That said, most VFD manufacturers (and by default, the lathe manufacturers) sell common-mode chokes that can be placed on the electrical lines to reduce emissions... something to consider.

[Ken Fitzgerald]

Dan,

I would suggest the frequency of the EMF emitted by the 3 phase converter too would determine if it would effect the pace maker. If the frequency is not within a range that the cardiac pacemaker is capable of receiving, it wouldn't trigger it or affect it's operation.

My cochlear implant was surgically implanted 5 weeks ago and gets activated next Tuesday. I am wondering how or if the 3 phase emition from my PM3520B will be detected by my cochlear implant. We'll see.

[Dan Hintz]

I would suggest the frequency of the EMF emitted by the 3 phase converter too would determine if it would effect the pace maker. If the frequency is not within a range that the cardiac pacemaker is capable of receiving, it wouldn't trigger it or affect it's operation.
Absolutely, but in the case of VFDs, the emissions will be across a wide range of frequencies... the question at that point becomes "Are the emissions in frequency range 'X' too strong?". On top of that, even if you're in the right frequency range, danger comes only from overwhelming the unit with high-power emissions... the chances of actually sending a false command are pretty much nil as random noise should look like a valid command in about 1-in-a-trillion chances.

My cochlear implant was surgically implanted 5 weeks ago and gets activated next Tuesday. I am wondering how or if the 3 phase emittion from my PM3520B will be detected by my cochlear implant. We'll see.
The emissions shouldn't cause you any issue. You'll have to correct me if I'm wrong, but the data transmitted to your implant should be digital, which means cyclic redundancy codes (CRCs) in the data stream will self-correct any spurious emission noise. Again, it will be an issue of the emissions from the VFD being so strong that the implant's weaker transmitter can't overcome it with a high signal-to-noise ratio (in this case, the "signal" is the implant's datastream and the "noise" is the VFD emissions). I'm not up on recent cochlear implant development, but it's possible they may even use spread spectrum transmissions over a limited frequency range to cut down on outside interference.

If the transmission is analog (unlikely, but possible), EMF emissions from the VFD will have a greater chance of swamping out the implant's signal. And if the implant's transmission frequency is in the right range, the VFD emission could even downconvert into the audio band (that would be bad). You'll know within a few seconds of standing next to your lathe, though...

Glad to hear (no pun intended) you'll have access to some auditory clues again :)

[Ken Fitzgerald]

What's interesting Dan.....the implanted electronics are NOT battery powered but strip the RF off the signal coupled to the internal implant and rectify it to provide DC power for the internal processor and current generators/stimulators for the electrodes.

I posed this question at the manufacturer's user website where I am a member. One of the guys there is a EE, bilateral implantee and is heavily involved in a lot of the clinical trials for the new products and software under consideration. He's a moderator there and I'm sure he'll respond shortly.

There are some interesting characteristics about the CIs. Some people have noise when the go through the metal scanners at the airport.....the card I now carry for the TSA ...has my name...my doctors name and phone number.....the serial number and model number of my implant.....it states what portions of the system....part of the externally worn sound processor CANNOT be x-rayed or damage will result.

[Paul Williams]

I have a pacemaker and turn on a delta variable speed midi. I have had no problems. Basically I was told that any motorized tool would be safe at a distance of one foot. I believe that it depends a lot on the individual and the particular pacemaker. I might not take the same attitude if I had a difibulator installed or if I was 100% dependant onthe pacer. In my case if my pacemaker recieves a signal that doesn't fit the profile it does nothing. The worst case is my unit would not pace while I was in the RF or magnetic field. It then resets itself when I am clear of the field.

For the quarterly checks I hold a strong magnet over the unit to shut off pacing so they can check my heart without the pacer. For that reason I don't place magnets in my shirt pocket or hold an electrical tool directly against that area of my chest. Mine is an older unit and programming and readout is down electromagnetically.

Newer pacemakers are communicated with via radio frequency and may be effected differently by emmissions from your VFD. However the companies have done a lot of research and testing with common RF signals found in our environment and I would bet that you will not have a problem unless you decide to take a nap and lay your chest on the VFD.

Best of luck. I know there are many of us turning with pacemakers so I suspect there is a way that will work for your friend.

[Jim Burr]

2-3 years ago, the Mayo Clinic tested over 200 electric devices on every piece of hospital currently in use. I remember that AICD's could fire while passing through store RFID reader...those annoying beams that scan mag strips and alarm if you try and steal a 60" flatscreen after standing in line for an hour. I don't remember the rest of the results, but it may be worthwhile to get some facts from 1) the Cardiologist 2) the manufacturer 3) the lathe manufacturer.

[Jon McElwain]

I can not help with mods or anything, but I know that Oneway has and RFI filter (http://www.oneway.ca/index.php?page=shop.product_details&flypage=flypage.tpl&product_id=24&category_id=27&option=com_virtuemart&Itemid=2) as an available option on their lathes.

[Ken Fitzgerald]

Jon that will prevent RFI caused by transmission via the AC lines. It shouldn't have an effect on the rfi caused by radiation through the air.

[David E Keller]

Do any of you guys speak English? If I ever have trouble sleeping, I'm gonna call one of you and have you talk all scientific like that... I'd be asleep in no time!;-)

[Ken Fitzgerald]

Yeah.....well we aren't good with medical terminalogy and related topics...... Doc!

[Kevin W Johnson]

Yeah, it's the VFD thats the issue. The turner in question mentioned there was something that required adjustment on the lathe headstock, and for that reason he's hoping to avoid shielding that will hamper this. I don't own a 3520b, so i will have to look at the one the club has at our next meeting in December. I'm going to send an email to one of our other members thats has the same lathe and see if he has any shielding ideas that will avoid the issue he's worried about. He mentioned something about remote mounting the drive, but i don't think that's a viable route to go. I'm thinking a brass screen faraday cage that can be opened easily may be answer.

[Eric Holmquist]

I don't know if the EMI field from the lathe can cause problems with the pacemaker, but there is another potential solution if it can. Rather than try and shield the lathe, shield the turner! A proper ESD smock will function as a Faraday cage around the wearer. This way the wearer is protected from all the EMI fields in the shop.

[Dan Hintz]

[QUOTE=Kevin W Johnson;1809835The turner in question mentioned there was something that required adjustment on the lathe headstock, and for that reason he's hoping to avoid shielding that will hamper this. He mentioned something about remote mounting the drive[/QUOTE]
If he's interested in swapping out the VFD for another one (about $300 for a good Hitachi), he can get a remote pendant, which would allow him to adjust speed and such without opening up the cage.

[Eric Holmquist]

One of the benefits of my job is that a co worker is an internationally regarded EMI expert.

He said my earlier suggestion of an ESD smock would not help with the magnetic fields, just the electrical fields. What he did suggest is as follows

The pacemaker has to be manufactured to some EMI resistance specification and that the manufacturer (maybe Medtronics) should be able to tell you what that spec is. UL/CE listed Power tools are made to some EMI emission spec. What it then boils down to, is the resistance spec of the pacemaker higher than the emission spec of the tool. Tech support from the pacemaker manufacturer should be able to advise you on the subject.

What me co worker did suggest is that AC VFD motors are very unlikely to be a problem, while DC Pulse Width Modulated motors could be very risky due to frequencies involved. So home shop machinist equipment like a mini-metal lathe or milling machine (HF, Enco, Grizzly branded Seig Industry stuff) would be higher risk than some sub 150 Hz VFD