PTS Flowbench Forum

I'll post the technical difficults I had with this setup, so that no one wastes their time repeating them

Old Grey wrote:

The setup is a 1mm stainless steel orifice disk with 0.020" clearance spinning between 2 6mm alum disks.

It spun well enough, but had uneven gaps all around the orifice plate - you can see them in the 2nd pic -.
Next I took the clearance gap down to 0.004" to force the gaps smaller, but the disk would gall the alum constantly jam on the swarf.
The ss orifice disk looked pretty wavy so we went for 1.2mm, in the hope that the flatter disk would put less pressure on the alum and not gall it.
I also got rid of the top alum plate and just ran the ss disk on the bottom alum plate only.
The disk would spin, but would eventually feel rough.
Upon disassembly I saw that the ss disk was still picking up alum and galling, and that means that ss is not compatible with alum when rubbing.
I came up with a fix where there is protruding brass ring inserts in the flow through holes and ball bearings embedded in the alum plates so that the ss disk never touches alum. But when I checked the flatness of the alum plates, I found out they were heavily warped (0.050")
I worked out that the alum plate is cold rolled and that the surfaces are in compression, so that when I specified the fancy scallops in the undersides, it relived the stress on one side and buckled the plates quite badly.

A bit of advice for people who don't have laser cutting experience. No one can actually predict warpage with thickness, because it's shape dependant - my disk is more warped near the small holes than the large holes -. You can touch a plate right after it's cut, and it's only warm, but laser is concentrated heat, so it will still warp thin plates. Also the person cutting has a different interpretation of how much warp is warped - I told him to use a thickness that wouldn't warp, and even though he thought the 1.2mm wasn't warped, it was warped more than I wanted -. If I was to guess I would say the SF600 disk couldn't be thinner that 1.5mm - their SF1020 test plate is 1.5mm -, or that the warpage in a 1.5mm plate is acceptable.

180 hours was what I was quoted by the constructor and the wood was precut, so add those hours in and it's even more. Mine were both over 200 hours, so it's quite feasible for a first timer that is fussy about quality taking that long. It's that classic case where the first time takes a long time, and each subsequent one takes less time. I'm sure you could knock one up quick, but look at a first timer that works with metal, and now has to work out how to use wood.

I will continue to read and critique knowing now that this is a quest for a perfect flowbench from a poor initial design and you are just the mechanic in the equation. Please re read this entire thread and consider your curt word to those you call the Panel.. You criticize Bruce based on the PTS plans and concept do to hours to build cost to build tools to build skills to build. This Rotary disk is an over thought poor implementation of a decent idea! to solve the rotation issue just lose the bottom plate all together embed an 2.5MM o-ring in the top plate to seal the orifice when in position, then use a cam lock on the disk rotation shaft that is sprung to drop the plate 5mm when unlocked. Then you unlock rotate to position then lock to seal. Not simple DIY but with all the equipment you have access to it is simple. Next issue is bidirectional shaft sealing in the indicator rotational shaft but this could be solved by using the same cam lock to compress the seal around the shaft.

Rick

1960FL wrote:

180 hours was what I was quoted by the constructor and the wood was precut, so add those hours in and it's even more. Mine were both over 200 hours, so it's quite feasible for a first timer that is fussy about quality taking that long. It's that classic case where the first time takes a long time, and each subsequent one takes less time. I'm sure you could knock one up quick, but look at a first timer that works with metal, and now has to work out how to use wood.

I will continue to read and critique knowing now that this is a quest for a perfect flowbench from a poor initial design and you are just the mechanic in the equation. Please re read this entire thread and consider your curt word to those you call the Panel.. You criticize Bruce based on the PTS plans and concept do to hours to build cost to build tools to build skills to build. This Rotary disk is an over thought poor implementation of a decent idea! to solve the rotation issue just lose the bottom plate all together embed an 2.5MM o-ring in the top plate to seal the orifice when in position, then use a cam lock on the disk rotation shaft that is sprung to drop the plate 5mm when unlocked. Then you unlock rotate to position then lock to seal. Not simple DIY but with all the equipment you have access to it is simple. Next issue is bidirectional shaft sealing in the indicator rotational shaft but this could be solved by using the same cam lock to compress the seal around the shaft.

Rick

I use the cam lock system in the POS bench, so I know what you mean. The shafts have close fitting nylon bushes, so they leak less than a SF600 anyway.


You must have read it wrong because I didn't criticise the PTS FB, it's the best in my eyes, it's just that the panel has forgotten what it was like when they built their first bench. I still maintain it is more a small business bench - any bench that size would be -, or at least a high end enthusiast bench.

It's quite an interesting question if someone can go from wood to calibrated bench in 32 hours, and since I was a estimator I'll give it a crack.

I think a cabinet maker can make the PTS in a day, but using 2 men and a fully equipped workshop - 16 man hours - $1000
2 coats of industrial 2 pack epoxy with a volume of solids at 65%, using airless, and a single colour - 4 hours $500, 2 colours - 6 hours $600
You could use 3 pack, single coat, single colour, taking 2 hours, but I don't think anyone will want to pay a $1000
2 days fit out, with an electrician accounting for at least ½ a day, 16 hours - your time no cost, electrician $500, time 16 hours.
Probably 1 day calibration, when you find out the cabinet maker didn't take "air tight" seriously and it has a leak, or at least a day sourcing parts - 8 hours.

Total for professionals doing a PTS for the first time - 44 man hours , $3000 labour, and part cost around $1500.

Factor in a first timer with just a circular saw and a jig saw or plunge router, that doesn't know enough about wood work and splits his first piece of MDF when he puts a screw in it, I would say tipple the time, 120 hours, and half the cost.
First timer that researched everything before hand, and now knows how to not split MDF, probably quadruple it - 160 hours
A perfectionist - 180 hours.

I'm not wood savy, so I had to look up everything or work it out, and that is what 90% of people are faced with. Research accounts for a lot of time, and should be added to construction time.

This is what I mean about the forum, because they took my small business comment as derision when in fact they didn't realise that because of the simplicity of the PTS it is probably the fastest to build. I'm just trying to get the panel out of it's rut and contribute more, and to think more that just sticking to their rhetoric - this is like a kind of reality intervention -.
The premise of the "small business" comment was to point out that the bench might be too big for the little guy, and that the panel should help more with non PTS stuff. Who knows, they might get established and buy a PTS.

This is what I mean about the forum, because they took my small business comment as derision when in fact they didn't realise that because of the simplicity of the PTS it is probably the fastest to build. I'm just trying to get the panel out of it's rut and contribute more, and to think more that just sticking to their rhetoric - this is like a kind of reality intervention -.

Ok Grey,

I will not post all my answers now but continue to contribute, first off I not a fan of mind games and playing games, my life is on my sleeve and what you see is what you get, but if you are on board with this FF (me), then I will give you the shirt of my back and access to my shop, just stay away from my Girl unless you want lead poisoning....

First you missed my suggestion on the clamping as your shown design causes to much air turbulence prior to entering the orifice, second I will say this and there is no getting away form it and if you look at Tony's design you will see he thought of it. The rotational shaft is to close to the orifice, this will cause a bifurcation of the air changing the speed that air enters the orifice in that segment, yes it will work but it will cause each orifice to have slightly different CD and this will be again different at higher or lower depressions. My design on the cam lock is to pull up on the shaft of the rotating disk to make it seal therefore the cam lock handle is just under the rotating knob/indicator and you can use a clean plate as in your first picture.

last without going into to much, you remind me of an old grey haired friend of mine he will trip over a $20 to get to Dollar.... and then Mid F&*% everything until he has used up all his spare time and is forced to make a decision...

I think a cabinet maker can make the PTS in a day, but using 2 men and a fully equipped workshop - 16 man hours - $1000
2 coats of industrial 2 pack epoxy with a volume of solids at 65%, using airless, and a single colour - 4 hours $500, 2 colours - 6 hours $600
You could use 3 pack, single coat, single colour, taking 2 hours, but I don't think anyone will want to pay a $1000
2 days fit out, with an electrician accounting for at least ½ a day, 16 hours - your time no cost, electrician $500, time 16 hours.
Probably 1 day calibration, when you find out the cabinet maker didn't take "air tight" seriously and it has a leak, or at least a day sourcing parts - 8 hours.

Total for professionals doing a PTS for the first time - 44 man hours , $3000 labour, and part cost around $1500.

This forum is slated on a DIY community which is the polar opposite of the above mentality this is the thought process that the marketing people at SF go through to charge you what they do for some plywood and Formica. If I go down this path the $14,000 US is a deal on the SF 600 geez I probably saved $5,000 I should go out for steak dinner (remember FF), but time is not always money, when Mama wants to get Jiggy do you think to yourself that the seven minutes I going to be busy given it to her is going to cost me $12.00? NOOOO your dropping trowel and saying to yourself I'll pay the kid across the street to cut my lawn Unless you plan on building Flow Benches for a living mind screwing the time you put into the project is all against what this forum is about.

In closing regarding the little man, the newbee the daddy please do my homework for me new member; I like all new projects even Kimi's though it took time to come around, What I and most of the panel as you put it don't like is the member that has not read the basics does not know even what the Delta P means and is just looking for a simple answer so he can work on his racing skate board. last many of us are not fond of the whole floating depression concept and DV is completely hypocritical in his writings and the concept is inversely related to what many of us understand about velocity profiles. Beside one who gets there questions answered should share with all and contribute, the forum lost it's greatest contributor this year and it saddens me that many choose not to share for the some unknown reason, it is not all just the panel....

Rick

PS. I only do this because I believe in Bruce and I believe in those that helped me get to where I am today from a Flow Bench perspective, those that contributed, read the old forum.

the forum lost it's greatest contributor this year and it saddens me that many choose not to share for the some unknown reason, it is not all just the panel....

Rick

I agree with you Rick ... John a big loss today ... the forum this very quiet...

I believe in the DIY spirit, the pleasure of building and learn from a lot of guys around here .. Bruce ..Rick..Tony..John and other nice guys is priceless

I went through about 20 clamping permutations in my head, and that one was the easiest for me. It's not perfect, but does it really have to be perfect when even the SF isn't perfect.

You misunderstood that labour quote. It had nothing to do with price, it was mainly stating the man hours to complete the job. The price was the commercial price that Bruce should sell them for if it was a complete unit like a SF. How much did Pavtek pay?

Now that I look back at it I realise that myself and most of the panel were probably wrong, not wrong in actual facts, but more a misunderstanding of the situation. Look at it from Kimi's stand point.

You misunderstood the Kimi quote. I never said Kimi was right, it was more a case of people telling him what to do without providing any detailed proof as to why they were right.

You need to relax. I know the new hater mentality is all around degrading our self worth every minute of the day, but if you just read things from the perspective of the writer, not as an attack on your person, it does make total sense.

The only problem we had with the original design was the threaded top. The acrylic was too thin with a 19mm bore and 25mm block, so that when we tapped the thread it cracked the well. We had to make another block again.

Old Grey wrote: You misunderstood that labour quote. It had nothing to do with price, it was mainly stating the man hours to complete the job. The price was the commercial price that Bruce should sell them for if it was a complete unit like a SF. How much did Pavtek pay?

There is absolutely no way you could compare the price of any of the larger flowbench designs to the standard PTS bench! Most of those flowbenches are a one-off build and are made to flow way over 600cfm@28" so the cost will be higher.

I can build a standard PTS flowbench for $3500 to 4000, ready to start flowing. At this time I am not building them complete although I have built some already. They were not painted outside that was left up to the customer. I do not see a big market for pre-made flowbenches when one can DIY and save $$$$'s

I painted mine outside with a quart of Rustoleum and a foam roller for less than $25, inside gets painted with white Kilz primer and Bulls-Eye sealer

I do have people building and selling a few PTS Flowbenches around the world for other people, what they charge for that service is up to them and is not a forum topic of discussion, it is a private deal between the buyer and builder.

Brucepts wrote:

Old Grey wrote: You misunderstood that labour quote. It had nothing to do with price, it was mainly stating the man hours to complete the job. The price was the commercial price that Bruce should sell them for if it was a complete unit like a SF. How much did Pavtek pay?

There is absolutely no way you could compare the price of any of the larger flowbench designs to the standard PTS bench! Most of those flowbenches are a one-off build and are made to flow way over 600cfm@28" so the cost will be higher.

I can build a standard PTS flowbench for $3500 to 4000, ready to start flowing. At this time I am not building them complete although I have built some already. They were not painted outside that was left up to the customer. I do not see a big market for pre-made flowbenches when one can DIY and save $$$$'s

I painted mine outside with a quart of Rustoleum and a foam roller for less than $25, inside gets painted with white Kilz primer and Bulls-Eye sealer

I do have people building and selling a few PTS Flowbenches around the world for other people, what they charge for that service is up to them and is not a forum topic of discussion, it is a private deal between the buyer and builder.

That's what I like to read, constructive information.

Wow, only $3500 to 4000 prebuilt, that's really good. I think there is a market for pre built, just look at Pavtek. Some small business sometimes don't have time, like the PTS guy I talked to, so it's better they just buy it finished, and use the hours making the FB making money working instead - they might make $1000/day, so it's only 3 days cost -

If I had plans I would price out the material list, just for curiosity, because time to any non small business doesn't count as a cost, only the material costs matter - my POS bench was about $200 with the 200 hours being inconsequential -.

I wonder if a smaller version of the PTS would grab more people, if it can be keep stable, because that would make it reachable to a larger market - people like one head users -.

I was thinking, if you could convert the PTS back to orifice disk, and replaced the DM with cheap PVC manometer tubes, you could cut the cost by $250. I know no one would be keen going back in tech, but it would make a high quality DIY FB around $1000.

Bruce, and I have been working on a small two motor Bench Top unit that would work for karting and small motorcycle type stuff, but this plan then includes a new DM that uses a lessor DP so we have more power with a slight loss in accuracy with respect to the PTS standard but well within the SF range of error. This unit could be put up on a shelf when not in use and till uses a reversing slider so you can truly flow in both directions. Two of the biggest motors will still only draw 17 to 18 amps at 120VAC US common in most garages in the country also.

Rick