Replies

1. 
   forestgirl | Jul 28, 2008 08:03am | #1

   Methinks the hallowed pages are here <click>.  However, it's possible that with the quite-risen price of petroleum products, PVC is no longer a significant savings over HVAC.

   forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

   
   

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   Edited 7/28/2008 1:04 am by forestgirl

2. 
   Dave45 | Jul 28, 2008 04:57pm | #2

   I'll never qualify as anyones "pretty", but I'll respond to your post anyway.

   I've never seen or used a "dedicated" plunge circular saw and can't quite understand why they're necessary.  (Of course, there are many things that I don't understand - but manage to do anyway. - lol)

   I've always made my plunge cuts with whatever circular saw I had handy - including one of those big-mother worm drives and have never had a problem.  You have to work carefully and keep a steady hand, but it's no big deal.

   The whole dust explosion thing (either from an ungrounded DC system, or from airborne dust near a furnace or water heater) is another of lifes mysteries.  IMHO, these are urban myths and will remain so until I see some documented cases to the contrary.  (FWIW, documentation does not include some anecdote involving someone's ex-wife's second cousin.)

   I should also point out that I'm only talking about small shop dust explosions.  There's plenty of documentation for grain elevators in mid-Kansas in August, but that's a whole 'nuther ball of wax. - lol

   
   

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   Edited 7/28/2008 9:58 am by Dave45

1. 
   KiddervilleAcres | Jul 28, 2008 07:02pm | #3

   Dave,

   As has been said noone has provided any conclusive evidence that either metal or PVC duct work is suspect and/or the cause of a dust explosion.  I'm inclined to think the impeller being metal or plastic may be a more candidate.

   I have heard it said that if a woodshop reached the level of dust contamination needed to cause an explosion the operator would have long since left the area.  That being said I would think that a small metal object hurtling through a dust collector and hitting the wing of a metal impeller might just cause such an explosion and not the ductwork itself.

   Methinks dust explosions are more likely caused by the debris collected as opposed to the vehicle chosen to convey same to the collector bag.

   Regards,Bob @ Kidderville Acres

   A Woodworkers mind should be the sharpest tool in the shop!

1. 
   Dave45 | Jul 28, 2008 08:32pm | #4

   I'm inclined to think ......, I have heard it said ......, I would think ......,  Methinks .....

   Bob -

   I'm no politician, but I can, have, and will change my mind in a heartbeat when shown proof.  The above phrases from your post, however, ain't proof.  Opinion and conjecture certainly - but not proof.

   To borrow and paraphrase Cuba Gooding Jr's line in Jerry Maguire, "Show me the proof!" - lol

1. 
   KiddervilleAcres | Jul 29, 2008 02:32pm | #8

   Dave,

   Show me the proof!

   Therein lies the problem, I think.  I purposely added I think as that's about all I can say.  I've researched all over the place (including the Bill Pentz site) to find any conclusive evidence that supports a correlation of static to PVC as a potential for a dust explosion and have found nothing.

   About all I can contribute is my own experience which is what my previous post was all about.  Right now my DC consists of a 1½ HP Delta 50-760 with a combination of flexible and metal ductwork. 

   I have seen instances (my own experience) where static buildup in PVC has caused clogging problems, but no explosions.  I've also felt the static buildup in PVC but not sure if it was the PVC or possibly coming from the DC itself.

   I chose metal for two reasons:

   1.  There was no conclusive evidence that I could find that stated employment of PVC was NOT a potential explosion issue; nor was I able to find any that said it is. 

   2.  I can and did ground the metal ductwork.  You can't ground PVC.

   This issue has been beaten to death here and everywhere else I could find and with no PROOF either way.  If you find proof please post it here so we all can have the answer.

   Regards,Bob @ Kidderville Acres

   A Woodworkers mind should be the sharpest tool in the shop!

2. 
   bobpowers | Jul 29, 2008 12:43am | #5

   I once took a course in woodworking at a local educational facility that had used PVC for dust collection. I don't know whether ground wires were used. They had a problem with dust clogs due to static electricity, no explosions. Switching to metal ducts eliminated the problem.

1. 
   BrianDerr | Jul 29, 2008 04:36am | #6

   My 18 gal. shop vac has given me a lot of 'hands on' experience with static electricity. After any heavy extraction the metal handle (one of the few metal parts on the machine) holds a charge that will only be grounded by my body the next time I adjust or position the vac. It actually hurts! Usually I just try to get it over with or dilute it by touching the handle often. Sometimes it gets me by surprise and those are the worst. So I guess I kind of see how a plastic duct system could cause a static electricity problem. I know I should see if theres an easy way to ground the handle, but just haven't gotten around to it.Brian

3. 
   mytulpa | Jul 29, 2008 06:03am | #7

   the thing about this saw is that it comes with a set of guide rails that the saw registers to? travels in?. something like that anyway. makes for very straight cuts.

1. 
   SARGEgrinder47 | Jul 29, 2008 05:52pm | #9

   I will have a close look at the Makita at the IWF Show in a couple of weeks as I was not aware that they came out with one. Depending on the cost it couldn't be that bad as the Makita is not a bad circular to start with.

   On the PVC.. I have a short run of about 10' of PVC with the remaining being flex pipe. I hook the large dust makers directly to the pipe as they are clustered around the cyclone purpose-fully to keep the run very short. After I build something (about every two months on average) I have my duct set up to dis-connect which I do at the time. Then I run a ram-rod through (as you would a cannon barrel) to clear any possible pockets that might have built up which have proved to be minimal and I do run the cyclone for hours at a time on occasion.

   Sarge..

   Edited 7/29/2008 10:52 am ET by SARGEgrinder47