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murph64
07-21-2008, 02:26 PM
Probably the age old question...

End user in this case is a 1.5HP Fray V/H mill

http://www.jeepaholics.com/support/files/murph/20080717131049_IMG_2325b.JPG

and the operator (me) is a just about a complete newbie.

How often will I be changing speeds, such that swapping a belt becomes a PITA? Not often I'd imagine, seeing as this thing is for my own use in my single car garage.

Given a 2HP VFD and RPC to be within 25 or so clams of each other, I'm leaning towards the RPC. What's the verdict of those with more experience?


Andy

hardtail
07-21-2008, 03:10 PM
For this single machine and the VFD superior speed versatility I'd go with a VFD, this is a low hp unit and they're pretty reasonable. The guys can recommend which model Teco etc and where the deals are...probably ebay. If you think you may one day be expanding machine of more hp of similar voltage an RPC maybe the way to go.

Nice machine, did it come with tooling? What voltage is it?

andy_b
07-21-2008, 03:18 PM
hey fellow Andy!
while i love RPCs, in this case a VFD would probably be the better choice. the VFD will certainly be a benefit with regards to speed changes. do you think you'd be getting any other 3-phase equipment, or is this probably the only one? if this is it, and the costs are pretty similar, then the VFD seems like a no-brainer.

andy b.

jacampb2
07-21-2008, 03:34 PM
Hey, welcome! That is the same mill we talked about on pirate, isn't it? I'm Wicked_s10 over there.

IMO, a well built RPC is the way to go. You can run several machines when you get them, and trust me, you'll get them, and you can always run a VFD off the RPC if you want that luxury. You have to keep in mind that most of the controls in the machine may run on single phase from the 3 phase inputs. Contactors and transformers inside the machine are not going to like the VFD output much, if at all.

Most people who go VFD rewire all of the other stuff in the machine to run off low voltage and control the VFD, it all depends on how big of a project you want. After I built my big RPC, I never worried about what the next machine I dragged home would require. In my case, my RPC has a big xformer as well and I get 460 3p as well as 220 3p. If you go with only VFD, you have to shop for a VFD for every tool you drag home...

Later,
Jason

hardtail
07-21-2008, 05:49 PM
I'm a RPC lover as well but if any future machines are similar hp he could just plug them into a single VFD one at a time, the VFD here will solve his belt changes and speed problems and likely get breaking too......

If he stays with 230/460 machines ok if he gets 575 then he needs more hardware. I agree more machines will likely follow you home.......LOL

murph64
07-22-2008, 12:26 PM
:flipoff2: :D

Jason -

Yeah, this is the one I asked about on Pirate...More pics of the machine and what tooling I also got are here - http://www.pirate4x4.com/forum/showthread.php?t=699461 It's a 220V 3PH unit with the vertical motor being 1.5HP and the horizontal is 1HP. There are a couple of electrical boxes on the machine, I'll take pics tonight or tomorrow and post them. Why would some of the electrics controls be running on 110? I don't know if it's a clue, but both the vert and horiz motors still use the original drum switches.

I was initally going to pick up this Teco model http://www.factorymation.com/s.nl/it.A/id.196/.f?category=32 but came across a deal on a 2HP 3ph motor. The interesting this, is I was told that a 2HP motor won't work as an idler on an RPC, and I can't figure out what difference it would make. Not that it doesn't have enough HP, but a 2HP unit won't work. Is that really the case? I think for the 25 bucks that the guy wants for the motor, I'll pick it up anyway. Am I correct in thinking a wash down duty motor is a pretty solid unit?

What other machines am I thinking of? A lathe would probably be the only other thing I can see myself getting. I already have a 4x6 bandsaw and a drill press and they both run on 110v (although I'm thinking of switching the DP to 220)


Andy

gellfex
07-22-2008, 12:47 PM
I had my mill, lathe and buffer on a homebuilt RPC for a decade, but now have all but the buffer on VFD's and have added a VFD controlled drill press. I hated always having to hit the RPC before using a tool, my prototyping style work patterns don't involve long sessions at one tool. Leaving it running all day seems wasteful.

I find I change speeds far more casually than I used to, to the benefit on my work. 2 of my VFD's were each bought at online auction for less than $70 shipped. The really sweet thing about a VFD drill is how easily you can tap with it after you set up the external controls. I rarely put on my tapping head anymore.

jacampb2
07-22-2008, 03:55 PM
I have no idea why you woul dnot be able to use a 2hp 3p motor for an idler. I have never heard anything remotely similar. The only specific rule I have ever heard repeated over and over is that the idler has to be 50% higher HP rated than the largest motor you are going to *start first* off it. I say start first, because supposedly, each additional motor you get running adds to the amount of HP that you can start. I did not worry much about it as I built mine with a 10Hp inverter duty motor. I figured if I ever bring home a machine with a motor bigger than 7.5Hp, I will have to build a bigger shop, and the RPC will be the least of my worries.

As for why some stuff runs on single phase, well in most cases the motor lines and other odds and ends are not switched directly, but through contactors (big relays) the contactors use a low voltage to pull in the higher voltage, keeps the higher voltage somewhat isolated from the operator. Also, coolant pumps or switched coolant circuits are typically 110, as are switched work light outlets. None of the stuff in the machine will be happy with frequencies outside of the 50-60Hz they were designed for. And VFD's themselves are not happy about having the load disconnected while they are running, unless you send feedback to the VFD to tell it to shut down as well.

As for washdown duty motor? I have never heard of it. Maybe someone else will chime in.

Later,
Jason

murph64
07-22-2008, 04:58 PM
I have since found that a washdown duty motor can withstand high pressure water, as in a food processing plant where stuff gets hosed down/powerwashed on a regular basis. I passed on this motor as it's only 2HP, and for a 1.5 HP machine, I'd need a 2.5 idler.

I asked in the other VFD thread (http://bbs.homeshopmachinist.net/showthread.php?t=29996) about running the VFD through the machines switches, because this mill has 2 3ph motors and I'm a little unsure how to wire them up if I'm supposed to go right from the VFD to the motor.



Andy

gellfex
07-22-2008, 05:32 PM
I asked in the other VFD thread (http://bbs.homeshopmachinist.net/showthread.php?t=29996) about running the VFD through the machines switches, because this mill has 2 3ph motors and I'm a little unsure how to wire them up if I'm supposed to go right from the VFD to the motor.
Andy

This mill has 2 spindle motors, a H & V? Hmm, If you went VFD you'd either need a switchover box or 2 units. I wonder if you can failsafe a switchover by using a 4 pole switch with the 4th on an E-STOP circuit, so any monkeying with the switch while the unit is running will kill the VFD (to keep it from being actually killed)

jacampb2
07-22-2008, 08:06 PM
The only way I see it working is to switch it with contactors. I don't have a lot of VFD experience, but my ABB VFD on my B'port says that it is acceptable to have a contactor, overloads, or even multiple motors on the same VFD, but ONLY if the low voltage contacts on the contactors or O/L's are wired to provide the VFD feedback of what is going on. Also, my manual made a point of specifying that there could be no R/C's or snubbers across the coils to catch the emf kickback. I currently run my motor with the original overloads because my VFD is way to oversized and the electronic overloads can't be set low enough to protect the 'ports little 2Hp motor.

My first two machines, a Gorton 0-16a and a Colechester 15x48 round head lathe, I never even considered a VFD for them. The Gorton is a 2 speed motor with step pulley drive, and it is not that inconvienient to adjust spindle speeds. A lot of times the difference between high and low motor speeds is enough for a lot of work. The Lathe, well it is geared head, so it is nothing to change speeds. The only reason I went VFD on my B'port, is that I wanted the CNC software to be capable of changing the speeds, that and my varispeed stuff was all shot to hell.

Most motors, and especially old machine motors are not meant to be used with a VFD. We have gotten in this discussion on here before, but but the root of it is that newer motors rated for "inverter duty" have a lot more iron in their cores, better cooling, and can handle the variable frequency better. Just about any 3 phase induction motor will run on a VFD, but they may not handle the lower or higher frequencies needed to get the variable speed part. Even my b'port which is relatively recent compared to my other machines, doesn't like to be run bellow about 30Hz. Fortunately I kept the back gear on it, and can get any speed I want with it from about 30-100Hz.

Later,
Jason

rantbot
07-22-2008, 10:16 PM
The interesting this, is I was told that a 2HP motor won't work as an idler on an RPC, and I can't figure out what difference it would make. Not that it doesn't have enough HP, but a 2HP unit won't work. Is that really the case?
No. I use a 2 HP motor in that application. Works just fine.

murph64
07-22-2008, 10:38 PM
No. I use a 2 HP motor in that application. Works just fine.


Interesting...


I was going to take the lazy way out and pick up an RPC panel from This guy on Ebay (http://stores.ebay.com/Anderson-Converters_W0QQcolZ2QQdirZQ2d1QQfsubZ0QQftidZ2QQpZ 2QQtZkm) as I'm still a little sketchy on what all I'd need to make one, and he's the one that told me "a 2 HP motor won't work".


So I should pick up the 2 HP motor, then?


This mill has 2 spindle motors, a H & V? Hmm,

Yup. Check out this thread (http://www.pirate4x4.com/forum/showthread.php?t=695230&highlight=fray) on Pirate, and you can see the horizontal motor to the right of the horiz arbor.



If you went VFD you'd either need a switchover box or 2 units. I wonder if you can failsafe a switchover by using a 4 pole switch with the 4th on an E-STOP circuit, so any monkeying with the switch while the unit is running will kill the VFD (to keep it from being actually killed)

Or something simpler - can wire the VFD to a receptical (like a 6-50R, only one for 3ph) and connect an "extension cord" to each motor? And whichever one I want to use, I'd plug in? REAL bootyfab, but it'll work.

Andy

hardtail
07-22-2008, 11:17 PM
Go to Practical Machinist and look under the transformer, phase converter, vfd section, probably one of the most informative sites for this on the net and lots of knowledgable guys willing to help, drawings to build your own.

jacampb2
07-22-2008, 11:45 PM
...lots of knowledgable guys willing to help...


Now that is kind of a stretch, don't you think?

This won't mean much to most of you, but it will to the OP:

I found the practical machinist board to be the Pirate4x4 of the machining world. I won't even go over there anymore after I found this place...

There is lots of info on building RPC's on line. I got all of my stuff surplus except the caps. I bought all of the caps at a local motor rewind shop, the owner was nice enough to let me root through his supplies until I found what values I needed. I got my basic design from a wood working web site, it came complete with some rough calculations to get you close on capacitance values. It worked out very well. If you like I can try and find the web site for you.

Later,
Jason

hardtail
07-22-2008, 11:55 PM
Well I have a lot of thoughts about PM and many not entirely positive, but this section I find very informative and helpful, I won't get into the faults with others......There is much the same helpfulness here but for this topic PM is the pot o gold.........I'm not familiar with pirate........

murph64
07-23-2008, 12:14 AM
I found the practical machinist board to be the Pirate4x4 of the machining world. I won't even go over there anymore after I found this place...


I was initally going to post "a bit of a rough crowd over there sometimes" :D If I read Millacron say something like "one Clorox on the rocks, coming up...." I wouldn't be surprised...



There is lots of info on building RPC's on line. I got all of my stuff surplus except the caps. I bought all of the caps at a local motor rewind shop, the owner was nice enough to let me root through his supplies until I found what values I needed. I got my basic design from a wood working web site, it came complete with some rough calculations to get you close on capacitance values. It worked out very well. If you like I can try and find the web site for you.

Later,
Jason

That'd be great. I'm trying to find RPCs For Dummies :o I've read the stickie at the top of the RPC section of PM, and the Hanrahan thesis a bunch of times but I'm still :confused:


Andy

jacampb2
07-23-2008, 12:27 AM
...I'm not familiar with pirate........

Pirate4x4 is probably the foremost internet resource for rock crawling and off road tech/information. It is also probably the most newbie unfriendly place on the internet though. I have been a member there for about 8 years. I spent a good year reading before I ever opened my mouth... 10 minutes reading the topics over there would teach you that is the wise course.

Somebody, evidently with a sense of humor, sent me to PM when I got my colechester lathe. It wasn't as bad as it gets on pirate, but I was told rather succinctly that there wasn't room there for hobbiest folks like me, and I should consider packing up and moving to HSM.

I did, and I have never looked back. IMO We have an excellent group of guys here. I know almost for certain that anytime I have a question I cannot find an answer too, of basically any variety, that there are several folks from all over the globe that are willing to take time and answer here. We have a lot of talent and from all walks of life. I find it a lot more interesting here than in the crowd of a bunch of "professional machinists" over there...

Andy, I will hunt that link down tonight. I'll get back with ya.

Later,
Jason

murph64
07-23-2008, 12:30 AM
Thanks Jason...

I found this - http://www.essortment.com/hobbies/rotaryphasecon_sflv.htm which clears up a few things.

My big question are the capacitors, I know they are needed, but I just don't get for what, and how big they need to be.

edit - http://homemetalshopclub.org/projects/phconv/phconv.html things are getting clearer.


WTF couldn't I find these links at work? I'd much rather do this on company time..:D

Andy

jacampb2
07-23-2008, 12:42 AM
Here is the page I used.

http://home.att.net/~waterfront-woods/Articles/phaseconverter.htm

After I found this one, I printed it out, and didn't even look any further for other instructions. It worked very well for me, and I had a balanced converter in probably 2-3 tries of fine tuning the caps.

As for caps, you need run caps, not start caps. Start caps are okay for the starting circuit, but even there be careful. My BIL tried to start the converter one day and held in the start button until one of my start caps exploded. I built it all in a gutted service panel on the wall in the shop, so he was perfectly safe, but he did have to change his drawers :D

I have been kind of working on a write up and pictorial instructions on RPCs, but I haven't had a lot of time to dedicate. I can email you some pictures though if you like.

Later,
Jason

murph64
07-23-2008, 12:53 AM
Pics would be AWESOME -



Andy

jacampb2
07-23-2008, 01:28 AM
I got your email earlier, so I have your addy. You may want to edit that out of the post or you will start getting a plethora of junk mail. Ask me how I know :p

I am at work right now, and just looked through my ftp server for my web page and I never uploaded the pics, so I wont be able to hook you up until tomorrow. I will try to remember when I get out of here for the night.

Later,
Jason

hardtail
07-23-2008, 01:54 AM
You are correct the "professional" tones are rather thick at times but it's their handle so I can't fault that, the tudes seem to be cyclic, at times almost unbearable but there is a ton of info and topics overthere if you can get past the initial unwelcome being a HSM type.

I was not questioning the knowledge and helpfulness here, great bunch of guys that fit like your most comfortable jeans, this place creates friendships.

Sounds like you have help on the way, murph a RPC is not a daunting task to build, amazingly simplistic in many ways that many electricians I know hadn't given any though to thinking outside the box myself included.

Your initial post was about belt and speed changes, hard to beat a VFD here. If you feel old ironitis is setting in a RPC would be better over the long haul, can be built in multiple arrangements as hp requirements change. I prefer the elcheapo route because I had many of the materials onhand and I don't use my machines everyday.

murph64
07-23-2008, 07:34 AM
I got your email earlier, so I have your addy. You may want to edit that out of the post or you will start getting a plethora of junk mail. Ask me how I know :p

I am at work right now, and just looked through my ftp server for my web page and I never uploaded the pics, so I wont be able to hook you up until tomorrow. I will try to remember when I get out of here for the night.

Later,
Jason

That's my work email that I sent earlier, and sometimes our network goons really have us on lockdown as to what gets "filtered".



You are correct the "professional" tones are rather thick at times but it's their handle so I can't fault that, the tudes seem to be cyclic, at times almost unbearable but there is a ton of info and topics overthere if you can get past the initial unwelcome being a HSM type.

That's why I've been signed up there since 9/03 and have all of sixtysomething posts. Most of it is waaay above my head, but I still lurk there *many* times a day. I'm not complaining - that's DTs site and he can run it as he sees fit.




I was not questioning the knowledge and helpfulness here, great bunch of guys that fit like your most comfortable jeans, this place creates friendships.



Sounds like you have help on the way, murph a RPC is not a daunting task to build, amazingly simplistic in many ways that many electricians I know hadn't given any though to thinking outside the box myself included.

Your initial post was about belt and speed changes, hard to beat a VFD here. If you feel old ironitis is setting in a RPC would be better over the long haul, can be built in multiple arrangements as hp requirements change. I prefer the elcheapo route because I had many of the materials onhand and I don't use my machines everyday.


Yeah, I was initally going for the VFD, but now lean towards the RPC as, like you said, it's simpler. And now that I'm beginning to understand how they are constructed, it's getting to be the cheaper route. And I also need to get the feel of the machine, which with the amount of free time I have, will take a while :(.

Andy

andy_b
07-23-2008, 11:59 AM
Here is the page I used.

http://home.att.net/~waterfront-woods/Articles/phaseconverter.htm

After I found this one, I printed it out, and didn't even look any further for other instructions. It worked very well for me, and I had a balanced converter in probably 2-3 tries of fine tuning the caps.

As for caps, you need run caps, not start caps. Start caps are okay for the starting circuit, but even there be careful. My BIL tried to start the converter one day and held in the start button until one of my start caps exploded. I built it all in a gutted service panel on the wall in the shop, so he was perfectly safe, but he did have to change his drawers :D

I have been kind of working on a write up and pictorial instructions on RPCs, but I haven't had a lot of time to dedicate. I can email you some pictures though if you like.

Later,
Jason


that is the page i used as well. my start cap is also on a push-button, and as long as you don't hold the button in for more than a few seconds, you should be fine. if your RPC idler doesn't spin up to speed in 10 seconds you have another problem anyway. i actually cheat with mine. my shaper is a 5HP (and so is my RPC idler). when i start the shaper i have to hold in the start cap button until the shaper motor spins up. once it does all is well with the world.

andy b.

jacampb2
07-23-2008, 08:20 PM
Okay, here are a few pictures of mine, also look at the RPC noise thread, there is a pic at the end of I believe commercially built RPC. Mine isn't as pretty, but it is damned simple.

http://www.rollmeover.com/bronco_fab/odds_n_ends/RPC/odds_n_ends001.jpg

These are ground buss bars for a entrance panel. I used them for distribution, they are available at the local home store for a few bucks for each long bar. I cut them up into what I needed and mounted them with nylon fasteners, with stand offs from the box.

http://www.rollmeover.com/bronco_fab/odds_n_ends/RPC/odds_n_ends002.jpg

This is the sub panel that I gutted out to use as an enclosure. It has the buss bars mounted.

http://www.rollmeover.com/bronco_fab/odds_n_ends/RPC/odds_n_ends004.jpg

I can't get this picture to upload right, regardless of what I try. Oddly, bellow is the same picture before I turned it, and it uploads and displays fine. weird...

http://www.rollmeover.com/bronco_fab/odds_n_ends/odds_n_ends004.jpg

Continued next post for the ridiculous picture limit...

jacampb2
07-23-2008, 08:21 PM
http://www.rollmeover.com/bronco_fab/odds_n_ends/RPC/odds_n_ends005.jpg

This picture is of the big entrance transformer I am using to get my 460V. Not necessary on 220 3p machines.

Later,
Jason

jacampb2
07-23-2008, 08:25 PM
As you can see, it is fairly simple. I used smaller caps in parallel until I found the right values to get my legs balanced, and then I got as close to those numbers as I could with individual caps. In the picture, the large disconnect is the 220 switch for the power to the RPC. The small switch lower is the start switch, It is a 30a DPST light switch, I have since swapped it for a pushbutton momentary switch. I never had trouble using it to start it, but it was an accident waiting to happen when others did it.

Later,
Jason

andy_b
07-23-2008, 10:27 PM
The small switch lower is the start switch, It is a 30a DPST light switch,

Later,
Jason

that is the SAME switch i use for the same purpose. yeah, i should get an actual pushbutton, but i'm too cheap and i'm the only one ever in my shop. if someone needs to buy a switch/button for their start cap, i'd recommend a pushbutton, something like a quality Allen-Bradley one.

andy b.

murph64
07-25-2008, 06:19 AM
One more, probably less than brilliant question...Does it really matter if the idler motor is 1700 or 3500 RPM?


Andy

jacampb2
07-25-2008, 07:45 AM
I can't answer that for sure, but I think I saw in the other thread that was going on that J_Tiers is running a commercial built one that is 3450. I can't recall ever being concerned about what speed the motor was when I was looking for an idler.

Later,
Jason

murph64
07-25-2008, 08:09 AM
I can't see where it would make a difference, but that's what I was told. Maybe these ready built RPC panels have specific parts inside that won't work with a 3450 RPM motor?


Andy