| ThingyNess |
I'm currently finishing mounting my two P3A boards in a 2U rackmount chassis, and I'm debating how I'm going to mount my toroid to the case.
I have two of them, both 750VA, one with a potted centre, and one, unpotted with two rubber washers and the metal mounting disc, along with an M10 bolt and nut to secure it. Unfortunately, the nut is about 1.5cm thick, and I have about 2mm clearance at the bottom of the chassis before I violate the 2U rackmount footprint. Since this amp *is* eventually going to be mounted in a rack, and I don't want to block one unit of rackspace below it, using the nut against the bottom of the chassis isn't an option, as I have only 2-3mm of space between the bottom of the chassis steel and the bottom of the aluminum faceplate, which exactly conforms to the 2U specs.
I debated just drilling/tapping a hole for the M10 bolt to thread into on the bottom of the chassis, and then just putting some threadlocker on it and shearing the bottom of the bolt off with a cutoff wheel, which will work, but I'm worried about the transformer coming loose, as it weighs ~15 pounds, and I do expect the amp to be moved a fair bit. Since the rackmount chassis is only 1.5mm thick steel, there will only be room for 1 and maybe two threads to be cut in the chassis, which doesn't seem like it'll be very strong to me.
My best idea has been to simply use the large metal mounting plate, inverted, against the bottom of the chassis, as it has a recessed part in the middle which the nut can sit against and not protrude out the bottom of the chassis. this will work, but I only have one of the mounting plates, and I have no idea where to get another one.
Does anyone have any creative ideas for mounting these things that I might not have thought of yet, or some easily-accessible hardware that might help?
I'm debating just asking plitron to send me a few sets of the mounting plates, although that's likely not going to be too cost-effective.
Thoughts? |
|
|
| Mad_K |
| quote: | Originally posted by ThingyNess
I'm debating just asking plitron to send me a few sets of the mounting plates, although that's likely not going to be too cost-effective.
Thoughts? |
If this solves your problem, try to explain them your perdicament. Maybe they'll help you out? (It costs nothing to ask...)
;) |
|
|
| Tazzy |
| Tywraps and sticky tape is no option? |
|
|
| lieven |
| fill the centre hole for 3/4 with hot glue or something similar. that way your centre bolt will de lower. |
|
|
| Helix |
| quote: | Originally posted by ThingyNess
I debated just drilling/tapping a hole for the M10 bolt to thread into on the bottom of the chassis, and then just putting some threadlocker on it and shearing the bottom of the bolt off with a cutoff wheel, which will work, but I'm worried about the transformer coming loose, as it weighs ~15 pounds, and I do expect the amp to be moved a fair bit. Since the rackmount chassis is only 1.5mm thick steel, there will only be room for 1 and maybe two threads to be cut in the chassis, which doesn't seem like it'll be very strong to me.
|
isn't it only sheet metal inwhich case, not much to tap into. However you could make a disk of metal about the size of the toroid core. Now screw this down with three/four smaller screws and tap the large hole in the center so u get at least a cm of the bolt in to the thread.
or some really thick tywraps, this sounds good too, if u wanna get it done quickly. |
|
|
| UrSv |
Could be done in many ways I suppose.
#1
Take a piece of metal and attach that with smaller screws to the bottom and then use a shorter bolt in the box to attach the transformer to the case.
#2
Use a sinker sleeve (or what you call them)
Like this? |
|
|
| ThingyNess |
UrSv: I like the look of your idea -- where would I acquire such a piece of hardware? Would a local home depot or such carry them?
Really thick Tywraps would likely be too thick, unfortunately.. as I said, I have like 2mm clearance at the bottom of the chassis, and most large nylon zip-ties are thicker than that.
Ditto with the mounting bolt SvErD showed. it looks like the head would be thicker than 2mm or so, which would make it protrude from the bottom of the case too much. |
|
|
| UrSv |
| quote: | Originally posted by ThingyNess
UrSv: I like the look of your idea -- where would I acquire such a piece of hardware? Would a local home depot or such carry them?
Really thick Tywraps would likely be too thick, unfortunately.. as I said, I have like 2mm clearance at the bottom of the chassis, and most large nylon zip-ties are thicker than that.
Ditto with the mounting bolt SvErD showed. it looks like the head would be thicker than 2mm or so, which would make it protrude from the bottom of the case too much. |
For option #1 you would have to find a suitable piece of whatever to drill and tap. For option #2 I have seen parts like that at Claes Ohlsson years ago but that of course is in Sweden...and whereabouts in Canada I wouldn't know. Try all the local oddbits suppliers and they might have something like it. Don't be picky about the actual intended use of the part as what I find usually was not meant for what I use it for in the end. |
|
|
| Jarno |
Hello all,
You could also try to mount the toroids using a two component epoxy, should be as strong as you'll ever need. Replacing the toroids is, of course, out of the question (short of using crowbars and the like). Just my two (euro) cents.
Regards,
Jarno. |
|
|
| DRC |
| quote: | | Ditto with the mounting bolt SvErD showed. it looks like the head would be thicker than 2mm or so, which would make it protrude from the bottom of the case too much. |
5 minutes work with a file could bring it (the coach-bolt head) within your 2 mm limit (still strong enough ?). The square hole you also need to make could take a little longer ...
Dave |
|
|
| Sandy H. |
Possible solution would be to use 2 part epoxy to attach a nut to the inside of the chassis. Be careful when tightening, though. It might take a little experimenting.
Good Luck.
S. |
|
|
| Mad_K |
| quote: | Originally posted by SvErD
I use these |
Me too. -Clas Ohlson?;) |
|
|
| SvErD |
| quote: | Originally posted by Mad_K
Me too. -Claes Ohlson?;) |
Or these (Biltema) |
|
|
| Mad_K |
| What is that? :confused: |
|
|
| SvErD |
| quote: | Originally posted by Mad_K
What is that? :confused: |
Don't know the english name, it's "mutternagle" in norwegian(crimp nut, nut rivet??) |
|
|
| Mad_K |
| That's what I thought.. Are you using those for toroid mounting? How? |
|
|
| SvErD |
| quote: | Originally posted by Mad_K
That's what I thought.. Are you using those for toroid mounting? How? |
You just drill a hole(9mm for a M6 screw) and insert/crimp the nut from the buttom. The rim is only 1.5mm thick. Good for mounting cirquitboards too. |
|
|
| pinkmouse |
Tried to write this down, it got too complicated so I made a quick demo model!:)
Make a bracket out of sheet metal as shown below, fix it to the bottom of the case with pop rivets, as seen in front of the model, (may be called different things in your area) then bolt through this as per normal. |
|
|
| Peter Daniel |
Any of those hardware would work and is available from a Home Depot near you. The bolt's head is exactly 2.1mm thick.
Using epxy and gluing a bolt to a chassiss is out of question, it will break off. |
|
|
| Helix |
tee-nuts ?
whatever for my dear watson ? |
|
|
| seangoesbonk |
Hey Thingy!
I was just going to post when Peter beat me to it...
http://www.leevalley.com/hardware/p...currency=1&SID=
Lee Valley(in Vancouver) sells these bolts in short or long, as well as various cap nuts, etc. All standard 1/4-20 thread and a head height of 2mm. Try looking around the LVTools website. You should be able to find something there. You might want to check to see if Home Depot has it first. It might save you the drive into Vancouver.
Good Luck! |
|
|
| sam9 |
Suggestion: Go to a hardware store ad buy a bolt of the apppropriate length and diameter but to the flat head variety intended to be counter sunk. Buy a couple of large washers with an inner hole whose ring is about the same diameter at the head of the bolt. Drill a hole where you want the bolt. Shove it through from the outside. Place the washers over the bolt on the inside. Fit the nut to the bolt. Tightenit - keep tighteninh it until it deforms the bottom pannel of you enclusure enough that it is flush with the surrounding surface. Sounds crude but woorks and looks much beeter than one would reasonably think. It works best with an aluminum enclosure.
Caution: It sounds like the transformer will have a tight fit. There will be a bolt through the center connected to the bottom of the enclosure. These are both conductors. If the the top of the bolt ot the top plate comes in contact with the lid of the enclosure, you will have a conduction pass in the form of a loop through the center of the transformer. This will induce a current (that's what transformers do, after all). I don't know the physics of it, but know from personal experience that this does happen! If the encluse is connected to ground you will simply blow the power supply fuse the monent you hit the on switch. If the enclosure is not grounded, you will have a live enclosure wating for you to become the path to ground! It is best to be sure there is clearance or insulation that prevents it from happening. |
|
|
| ThingyNess |
Thank-you to all for your help.
I think i'm going to lee valley like sean suggested and pick up some of those nuts. I had also forgotten the T-nuts like Peter showed. Silly me - I use them all the time for speaker building and I never realized that they'd bite into metal just fine as well.
And thanks for the warning about the shorted turn, sam9 - I accidentally did that once before - produced quite a bit of heat and buzzing - luckily I didn't blow my toroid. There's about 5mm between the top of the mounting plate and the chassis with this toroid, which will be enough as long as nobody puts enough weight onto the top to deform it and cause the hated shorted turn. I think I'll probably spray the top of the metal mounting plate and the top of the bolt with some truck bed liner to insulate it and prevent such an occurrence.
Thanks again! |
|
|
| GuySmiley |
| Since you are in Vancouver the original home of Mountain Biking I will suggest head down to your nearest bike store. The nuts used to hold the chain rings together are exactly the kind of T-nuts you need and you won't have to wory about biting into the metal. Just a thought if it is more convenient for you... |
|
|
|
