PDA

View Full Version : Vacuum chuck system build WIP



Hermit
29th June 2014, 01:09 AM
After receiving so much help from everyone here on vacuum chuck system design, threading wooden faceplates etc, I thought I'd post a short pictorial WIP of the build.
It's not far from finished, so I can cover a fair bit of ground in this first post.

This is the 3.3cfm vacuum pump I'm using. A cheap score from eBay at $100:

318196


These are the main components below. Top left is a micro-adjustable needle valve, a bleeder, for adjusting the vacuum level.

At the top right is a lever-operated ball valve, another bleeder, for releasing the vacuum. I used a separate valve for this so that the needle valve could be left as-is after adjusting, while releasing or re-positioning a work piece using the lever ball valve.

Bottom left is the vacuum gauge, 0-30 inHg. (-1 bar)

At the bottom right is a sintered bronze 40 micron inline filter, intended for use with a spray gun:

318197

I'm still waiting on a couple of small sintered bronze 1/4" BSP filters to go into the inlet side of the bleeder valves, to keep the crap out. The main filter is set up to only filter the air from the vacuum chuck.

The other main component is the bearing assembly for the rotary adaptor that attaches to the handwheel. This is two 47.5mm x 13mm bearings, pressed side-by-side onto a hollowed brass rod with a 1/4" BSP tapered female thread cut into one end to take a brass hose fitting. My mate Jack in Sydney knocked this up for me - the heart of the adaptor. Before I assemble everything I still have to grind a small flat on each side of the protruding part of the brass rod, to get a spanner onto for tightening/loosening the hose fitting. Jack left that bit to me.

318207 318208 318206


To make things easy, I've gone with 1/4" hosetails on all parts, so I can use cheap 6mm ID silicon vacuum hose to connect everything and for the chuck seals, I bought a metre of 2.5mm closed cell neoprene foam:

318198 318199


The first of the vacuum chucks, a flat disc 230mm in diameter. Actually, not quite flat - I dished it very slightly, about 1.5mm deep in the centre, so it could hopefully hold flat discs better. The small green thing in the centre is a pre-filter - two 1" discs cut from a Scotchbrite scouring pad and glued around the outer edge to hold them together. It'll hopefully stop so much junk from reaching the main filter.:

318200 318201


A test-fit of the main parts. I made a plywood stand to hold everything together:

318202


The next step is the rotary adaptor for the handwheel. Finally, a bit of turning. I'm using a two-piece assembly. The main part, containing the bearing, fits up onto the front of the handwheel with a neoprene seal to prevent leakage, and is held in place by a clamping ring behind the handwheel. To clamp the two halves together I'll drill four 6mm holes through both pieces, thread some allthread into one half, then use countersunk nuts with washers.
So far, I've turned the recesses in both halves for the handwheel and the bearing. I only need to reverse-mount the main part tomorrow and cut an access hole for the brass fitting to protrude from. The Gods were with me and I got a beautiful firm sliding fit for the handwheel and the bearing.

318203 318204

318205 318195


To be continued......

chuck1
29th June 2014, 12:24 PM
Looking forward to seeing this in action! If you want to try it on a bigger Lathe you can come over!

Hermit
29th June 2014, 07:26 PM
Looking forward to seeing this in action! If you want to try it on a bigger Lathe you can come over!

Actually, if you can organise the handwheel rotary adaptor part to suit one of your lathes and a vacuum chuck or two to suit your spindle thread, you'll be welcome to borrow it when I'm not using it. (My thread is 1" 10tpi.)
I can't remember, do any of your lathes have a vacuum fitting on the side of the headstock? That'd make it real easy. We could soon make an adaptor to suit my 1/4" BSP female fitting on the end of the hose.


This is a bit long-winded, but I wanted to cover as many points as possible, for any one else planning to build one:

I got side-tracked today and didn't get as far as I'd hoped, but I did get the vacuum access hole in the handwheel done, along with a bit of rounding on the edge to make it more handwheel-like. I'll reverse the other half tomorrow and round the corner to match. I still need to bore and thread the holes etc for clamping the halves together then.
The 45 degree elbow on the fitting is only temporary. I have a 90 degree one coming, to keep the hose further out of the way. (To stop it twisting with the rotation from drag in the bearings, I'm making a small bracket to mount on the end of the lathe bench, with a fitting to hold the hose in place.)
(And please ignore the crappy quality ply - it's all I can get hold of, short of buying the 10mm hobby stuff online.)

318299 318298


I didn't mention earlier, but when I press the bearing assembly into place during final assembly, I'll push it most of the way home, then put a smear of epoxy around the outside of the last bit of the second bearing and press it the rest of the way in. Should stay in place.

Also, I was concerned about a vacuum leak down the thread of the handwheel, but found that when it's tightened there's a small recess at the base that will hold a 17mm ID, 2.5mm thick 'O' ring, so I've ordered a few. That takes care of the potential leak at that end.

For the other end, at the base of the vacuum chuck itself, I'll use Blu-Tak around the base of this first vacuum chuck, (if needed), each time I put it on, but for future ones I'll try to cut an 'O' ring groove at the base and buy some 'O' rings to suit.

To ensure that there are no leaks through the ply, I'm sealing all of the parts well with poly inside and out, and the vac chuck thread is sealed with 3 rounds of CA followed by re-tapping each time.

Hermit
29th June 2014, 07:38 PM
Just in case anyone's interested, here's the handwheel plan (for a Pop's Shed mini-lathe handwheel). I had to stray slightly from the dimensions shown. The ply halves ended up being 18mm and 36mm instead of 19 and 37.
(It says full-scale, but it's not any more - I resized & converted to jpg for the forum.)

318301

chuck1
29th June 2014, 09:29 PM
Let me know what O rings you want the cheapest place is near my work and I'll grab them for you, they have a huge range of sizes
could you use Teflon gas Plumbing tape on the thread?

Hermit
29th June 2014, 09:46 PM
Let me know what O rings you want the cheapest place is near my work and I'll grab them for you, they have a huge range of sizes
could you use Teflon gas Plumbing tape on the thread?

Very kind of you to offer, Charlie, but it's OK - I ordered some for the handwheel seal on eBay last night, 17.2mm ID, 22mm OD, 2.4mm thick.

I thought about just using teflon tape, but it's a lot of messing around and more importantly, I thought it might make it a bit hard to get the handwheel or vac chuck off again, since they aren't tapered. I don't have a spindle lock, so have to be careful in that regard.

An 'o' ring can stay permanently on the handwheel end of the spindle, and I'll fit one into all of my vacuum chuck bases from now on. Not sure what diameter I'll need for that yet, but probably 1/8" thick to suit a parting tool groove. I'll make the groove just deep enough to partly compress the 'o' ring while still allowing the base of the chuck to seat firmly against the collar. Probably glue the 'o' ring in place in the groove.

Pity, I bought 2 rolls of teflon tape the other day, for putting together the brass fittings, but will probably never use it for anything else.

Christos
1st July 2014, 10:23 AM
Cool I will pull up a chair and follow this one. :)

Paul39
1st July 2014, 02:12 PM
Hermit,

Very nice tutorial.

Thanks

Hermit
1st July 2014, 08:03 PM
Cool I will pull up a chair and follow this one. :)

Welcome aboard Christos. Hopefully you won't have to hold your breath for too long.



Hermit,
Very nice tutorial.
Thanks

Thanks Paul. Not that I'd really call it a tutorial though. I hardly know what I'm doing. Despite that, so far so good. Let's just hope I don't have too many leaks to fix at the end.


I've been busy on my other projects, but have made a little more progress.
The mini sintered bronze filters arrived yesterday. One less thing I'm waiting for. They go on the inlets of the bleeder valves as shown, to keep dust out of the system.

318473 318472


I cut a neoprene gasket for the facewheel seal last night, too. Initially, it had me scratching my head about how to mark the circles for cutting out. Black pen on black neoprene doesn't work well. Then, a brainwave - I put my scalpel-style hobby knife into the compass instead of a pencil, then went around the outline lightly several times until right through. It worked a treat. I'll glue it in place when I finally assemble everything else. A little messy on the ID, but that's only because I used a blunt blade. :-

318476 318475


I also got the holes drilled and tapped for the handwheel clamp studs and cut the studs. To avoid getting hit in the knuckles by the nuts, I recessed them fairly deeply, a couple of mm below the surface when tightened. I made a bit of a mess of the holes in the pic above, but filled the tearout with epoxy.

318477


I'm just putting a few coats of poly on these parts now, then I can press the bearing in and fit the studs.
I'm still waiting on a last few odds and ends before I can assemble everything, but hopefully they won't take too much longer.

If anyone sees a better way of doing something, or a detail I've overlooked, please let me know.

Mobyturns
1st July 2014, 08:08 PM
...... I don't have a spindle lock, so have to be careful in that regard.

......


I came across this simple solution on a website the other day hidden in here

Other Lathes (http://home.comcast.net/~kvaughn65/otherlathes.html)

Go to
http://home.comcast.net/~kvaughn65/spindle_stop_1.jpg
http://home.comcast.net/~kvaughn65/spindle_stop_2.jpg

Hermit
1st July 2014, 08:45 PM
I came across this simple solution on a website the other day hidden in here

Other Lathes (http://home.comcast.net/~kvaughn65/otherlathes.html)

Go to
http://home.comcast.net/~kvaughn65/spindle_stop_1.jpg
http://home.comcast.net/~kvaughn65/spindle_stop_2.jpg

Thank you for that Moby. Not a bad idea, and it looks pretty easy to make. I'll have to see if I can come up with something similar.
I keep putting it off, but I'll regret that the next time the chuck gets stuck on the spindle. Last time, I clamped a 12" bar tightly in the largest chuck jaws then struck it sharply with the heel of my hand and it spun free. I don't like doing that, though. I'd hate to damage the chuck.

crowie
1st July 2014, 09:24 PM
G'Day Steve, You are sure doing a top class job on the WIP c/w notes....well done sir, cheers, crowie

Mobyturns
1st July 2014, 09:36 PM
Thank you for that Moby. Not a bad idea, and it looks pretty easy to make. I'll have to see if I can come up with something similar.
I keep putting it off, but I'll regret that the next time the chuck gets stuck on the spindle. Last time, I clamped a 12" bar tightly in the largest chuck jaws then struck it sharply with the heel of my hand and it spun free. I don't like doing that, though. I'd hate to damage the chuck.

Depends upon the design of the head stock spindle, but sure better than destroying a flimsy indexing pin. The old woodfast's have a hex "nut" machined into them, so no problem at all.

Hermit
1st July 2014, 10:51 PM
G'Day Steve, You are sure doing a top class job on the WIP c/w notes....well done sir, cheers, crowie

Hello Pete. Thank you for the kind comment. I haven't done a WIP of any sort for a while.
I hope someone finds it useful in future when doing similar.


Before continuing with the finishing, I decided to do a quick test-fit of all the handwheel parts, to make sure it would go together OK. No problems. It slides together beautifully. I can't wait for the last bits and pieces to arrive now. They're coming from Asia and the UK, though, so it might be a week or two.

Meantime, I can get the finish on. As you can probably see from the pics below, I'm coating the outside of each half with epoxy before the poly, to fill tearout and ensure there are no potential leaks through the crappy plywood. I haven't done the clamp ring yet, just the main body. The clamp ring doesn't need it, since it doesn't have to be airtight, but I want the finish to match. (It's gotta look pretty.) I'm also filling all visible cracks/defects the same way.

I've tapped for the studs, but to make sure they don't move I'll wait until I've got them in then dribble some thin CA down into the thread to wick in and lock the studs.

That's still a temporary vacuum fitting in the pics - I'll swap to a 90 degree elbow when it arrives.

318482 318483 318481


I'm waiting on some 11mm spring-type hose clips, too, along with a set of four 21mm castors so I don't have to lift the main unit to move it.

Rod Gilbert
2nd July 2014, 09:59 AM
Hi Hermit and all I will be following also just came across you're thread. I am enjoying the build it's looking very good so far, you're description and WIP photo's are great clear and defined.(keep up the good work we will be watching)
Regards Rod.:2tsup:

Hermit
2nd July 2014, 05:14 PM
Hi Hermit and all I will be following also just came across you're thread. I am enjoying the build it's looking very good so far, you're description and WIP photo's are great clear and defined.(keep up the good work we will be watching)
Regards Rod.:2tsup:

G'day Rod. Thanks for your interest. Hopefully it will all work well when done, without much fine-tuning, (leak sealing). I'm sort of feeling my way along, learning as I go, so there's bound to be a bit of trial and error before it's completed.


I gave the vacuum pump a test connected only to the vacuum gauge in a closed system. It pulled a vacuum of 27 inHg, (27 inches mercury). Not too bad at all - a perfect vacuum at sea level would be 29.92 inHg. (1 atmosphere)
Incidentally, 27 inHg means that the vacuum can pull a circular column of mercury 27 inches upwards, against gravity.
The formula for calculating the total holding pressure, (P):
P = pi x r2 x 0.491 x inHg (1 inHg = 0.4912 psi at sea level)

From the formula, with a 10 inch diameter bowl, 27 inHg would result in 1041 pounds of total pressure holding the bowl in place. Hence the vacuum adjust bleeder valve. I don't want to crush any thin-walled bowls. Generally, according to the 'Bruised Brothers' video, only about 75 pounds to 250 pounds of total pressure is needed.
So a 10" bowl would only need 5 inHg to get a pretty decent 193 pounds of holding force.

A handy chart:

318505


No parts in the mail today unfortunately, so I'm continuing with a couple more coats of poly inside and out to ensure a good seal. Although the vacuum pump can pull a good strong 27 inHg vacuum, it can't move much air, only 3.3cfm, so the whole thing has to be virtually leak-free to work well.

hughie
4th July 2014, 10:03 AM
G'day Rod. Thanks for your interest. Hopefully it will all work well when done, without much fine-tuning, (leak sealing). I'm sort of feeling my way along, learning as I go, so there's bound to be a bit of trial and error before it's completed.


I gave the vacuum pump a test connected only to the vacuum gauge in a closed system. It pulled a vacuum of 27 inHg, (27 inches mercury). Not too bad at all - a perfect vacuum at sea level would be 29.92 inHg. (1 atmosphere)
Incidentally, 27 inHg means that the vacuum can pull a circular column of mercury 27 inches upwards, against gravity.
The formula for calculating the total holding pressure, (P):
P = pi x r2 x 0.491 x inHg (1 inHg = 0.4912 psi at sea level)

From the formula, with a 10 inch diameter bowl, 27 inHg would result in 1041 pounds of total pressure holding the bowl in place. Hence the vacuum adjust bleeder valve. I don't want to crush any thin-walled bowls. Generally, according to the 'Bruised Brothers' video, only about 75 pounds to 250 pounds of total pressure is needed.
So a 10" bowl would only need 5 inHg to get a pretty decent 193 pounds of holding force.

A handy chart:

318505


No parts in the mail today unfortunately, so I'm continuing with a couple more coats of poly inside and out to ensure a good seal. Although the vacuum pump can pull a good strong 27 inHg vacuum, it can't move much air, only 3.3cfm, so the whole thing has to be virtually leak-free to work well.

Thats a good result. By the look of it I thought might be a vane pump but the figures are a bit high for such a pump design. A very good WIP thoroughly enjoyed it and will keen to hear how it goes in practice.

Hermit
4th July 2014, 01:45 PM
Thats a good result. By the look of it I thought might be a vane pump but the figures are a bit high for such a pump design. A very good WIP thoroughly enjoyed it and will keen to hear how it goes in practice.

Thanks hughie. And you're spot-on, it is an oil-bath rotary vane pump. I was surprised to see it could pull 27 inHg too, but I'm not complaining. :wink:
I guess it needs to go that high (low) to be able to properly evacuate an AC system.
Edit: I just did another test, set up better, and it actually pulls 28 inHg. It really sucks! Better still.

318667


The parts are slowly trickling in. I've finished the handwheel assembly and started putting together the parts I have, while I wait for the rest. So far, I have no leaks, not even from the handwheel assy, apart from where the two grub screws go through the handwheel base. (Overlooked that one.)

318668 318666

A bit tricky to seal, so I've settled on using a small blob of Blu-Tak on each after I fit it on the lathe, then a few wraps of tape to make sure they stay in place. For the test, I also used used an extra, big blob of Blu-Tak to block the spindle hole in the handwheel as well.
In the long run, I'll try to find an extra-small diameter bicycle tube and cut off an inch to form a 'collar' around the base of the handwheel, over the tops of the grub screws. I'm open to better suggestions for this.
With that done, according to my *high-tech testing, it doesn't leak at all.:2tsup:

* High-tech vacuum testing - block all except one hole, suck on it by mouth to create vacuum then place tongue over hole and wait to see if the vacuum fades off. I can get a 10 inHg vacuum that way.

I'm quite enjoying this build, but I'll be happier still when it's finished and I can actually use it. I've been dragging my feet on a plate I'm making, hoping to use the vac system to finish the bottom for a debut run.

hughie
4th July 2014, 02:10 PM
I had a look on Ebay and the price is very good. Oil bath that explains the extra ommph! :U mine is with out so it pulls around 55%, probably be ok over a large area. The vacuum chuck has on and off my to do list for a few years, cant make up my mind.

Hermit
4th July 2014, 02:24 PM
I had a look on Ebay and the price is very good. Oil bath that explains the extra ommph! :U mine is with out so it pulls around 55%, probably be ok over a large area. The vacuum chuck has on and off my to do list for a few years, cant make up my mind.

Yeah, mine was only $100, here (http://www.ebay.com.au/itm/Electric-3-6CFM-Single-Stage-1-4HP-Rotary-Vacuum-Pump-Refrigerant-R12-R22-R134-/131127571259?pt=AU_Gadgets&hash=item1e87cff33b#ht_4004wt_996). (The listing says 3.6cfm, 60Hz operation, but it's really for 50Hz and 3.3cfm.) Quiet running and smooth, high vacuum but, as mentioned, only 3.3cfm / 1.5 litres per second. Not bad, but a higher cfm rating wouldn't go astray, to compensate for any leaks. The bigger pumps of this type can move up to about 10cfm, but you pay for it. They're not so cheap.

Hermit
5th July 2014, 08:42 AM
I decided last night to use cable ties in pairs to clamp the hoses, instead of waiting for the spring clips to arrive. I think the cable ties do a better job.
So I went ahead and got most of the plumbing done. So far so good - I can block the end and still pull 28 inHg, and both the vacuum adjust and grip/release valves work well.

318746

I only need the 'o' rings and a couple of other incidentals and I can finally test it properly.

N.B. The circular hole in the RHS of the base is for oil-changing, to avoid having to remove the pump. It's directly below the oil drain plug.

Edit: I forgot to mention - I found that the neoprene seal that I made for inside the handwheel assembly crushed too much when firmly clamped up by the bolts, so I've ordered some 1.5mm 'natural insertion' rubber sheet, to make a better one. It won't compress as much.

Christos
6th July 2014, 12:08 PM
Very nice and neat setup.

Hermit
6th July 2014, 01:09 PM
Very nice and neat setup.

Thank you mate.
I've got a bit of an update....

I'm way too impatient to wait any longer for parts to arrive, so I searched around and found a rubber washer with the right thickness and ID for the handwheel spindle seal and trimmed the outside to size. (The washer came from a garden hose fitting that screws onto a tap - 3/4" ID.)
It sealed well, so I bodgied up a temporary short straight length to go to the rotary adaptor and set everything up. (I've got a 4" male to male fitting ordered to replace the two m-m bits and the f-f bit that I'm substituting with. Two less joints to fail.)

To ensure that bearing drag doesn't pull on the hose, I made a small wire bracket to keep things in place:

318807


I also made a small, neoprene padded disc for the tail centre to hold the piece against the chuck disc when the vacuum is turned off. (That bowl is the first bowl I ever made some time back - 6" diameter, QLD Maple, finished in a few coats of WOP so I knew it would seal well for testing.):

318808


First test, vacuum on and adjusted to 10inHg, but lathe turned off still. I found that the 'grip/release' lever is very useful for centring a piece that doesn't have a marked centre - I can back it right off until the piece is just gripped, allowing me to slide it around while sighting against the end of the toolrest:

318809 318806


Second test - lathe running at 1000 rpm, vacuum at 10 inHg still. I didn't want to go higher because 10 inHg on this 6" bowl is already 139 pounds total holding force. I definitely can't budge it.

318810


It works great. I'm really pleased with it so far. The only thing I can't do just yet is any turning using it. I don't have a bowl at the right stage. I have to wait a day or two until I put another finish coat on the top of a plate I'm making, then I can turn it over and test the vac system fully.
After today's test, I already know that will go well.
I'm a happy camper - I didn't waste all this effort.

Oldgreybeard
6th July 2014, 02:34 PM
Congratulations. A first class job.
Bob

Hermit
6th July 2014, 08:57 PM
Congratulations. A first class job.
Bob

Thanks Bob, for your interest and your kind comment. :2tsup:
Also thanks again for your help the other day. :cool:


The only thing I'm not too sure of now is just how much pressure to use for a given bowl/plate size. The 'Bruised Brothers' vid says to stay between 75lb and 250lb, from memory, but that doesn't help a real lot. I'll do a 'Google' and see what I can come up with.

Hermit
15th July 2014, 11:28 AM
I've had the chance now to give this system a really good workout. It works beautifully, except for one little drawback - the 2mm neoprene I bought actually varies from 2.5mm to 4mm thick across it's width. Not the best for finishing the rear of a plate rim.(Wish I'd noticed before I glued it on. I blame my glasses. Time for a new pair. )
I contacted the seller, and he's sending me some that he's checked for consistency first. Also, this time I'm getting it with an adhesive backing, to save messing around with spray adhesive.

The second fix isn't so much a bug, as a precautionary measure. In my travels, I've read of a couple of cases of bearing seals popping inwards under maximum vacuum, resulting in a sudden loss of vacuum and a UFO. It sucks much of the grease out of the bearing and into the vacuum system too, apparently. Not good.

To help prevent this, I machined up a disc of 5mm acrylic, to act as a sort of seal retainer. I routed a groove for the bearing rim and a step, so that the acrylic sits firmly against the surface of the rubber, pressing it into place. It's held in place by four countersunk screws.
If the seal can't deform inwards, hopefully it'll never pop. I don't mind a gradual loss of vacuum over time as the seal wears, but don't want that sudden 'let go'.

319659 319658

Simplicity
15th July 2014, 09:51 PM
Hermit
I've been following this built from behind a sheet
Not having any thing use full to say.
But now it's all most done it looks fantastic and seems to be working a treat.
Well done
Something I hope to do one day my self

Hermit
16th July 2014, 10:37 AM
Hermit
I've been following this built from behind a sheet
Not having any thing use full to say.
But now it's all most done it looks fantastic and seems to be working a treat.
Well done
Something I hope to do one day my self

Thanks for that mate.

It's well worth the effort. No more plywood discs with tabs for reversing & finishing bowls, plates etc.

One thing I really like is that unlike with a Longworth chuck or Cole jaws, you can work right to the edge of a plate without the rubber stoppers getting in the way. And it's sooo easy to use.

Next up, when I get some more 3/4 plywood, is a few cup chucks, for natural-edge bowls and smaller items. 2", 3", 4" and 5".
I'm not sure how the 2" will go - I'll need as much vacuum as possible, but we'll see. Even with the maximum 28 inHg of vacuum, the total holding pressure on a 2" item is only 43lbs. I'm not sure if that's enough. On other larger items, 4" to 6", I've found that about 120lbs to 150lbs is pretty good.

I've really enjoyed building this. A bit of a change from all the decorative stuff, and my first real precision turning on the handwheel adaptor.

Edit: The new adhesive-backed 2mm neoprene just arrived. It looks much better - a nice consistent thickness. In case anyone else is looking for some, it's here (http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=300963747516&ssPageName=ADME:L:OC:AU:3160). (To get adhesive-backed, you need to specify it in the purchase note. Same price.)
It's thin enough to not be too spongy, and grips like s@#t to a blanket. The neoprene is sort of 'sticky'. You need to back the vacuum off to almost zero before you can move the workpiece.

Simplicity
4th August 2014, 09:26 PM
How's the vacuum chuck going now hermit
Now that you have at some time to play with it
Matt

Hermit
4th August 2014, 09:45 PM
How's the vacuum chuck going now hermit
Now that you have at some time to play with it
Matt

Really good, Matt. I've used it a few times now and it performs beautifully. Still pulls 28 inches of mercury when both bleeders are closed.

The only fault, if you can call it that, is that the little pump gets hot pretty quickly. Much more than 30 min in one go and it's almost too hot to touch. I give it 15 minute bursts, then pull up the tailstock with a padded disc and give the pump a break for a bit. Cuppa time.

I have a small 6" desktop fan on it now, which helps a lot, but in the longer run I'll either buy a bigger fan or a bigger pump. Probably the former.

I still haven't made any vacuum cups to go with it, either. Only the flat disc so far. I'll make them as I need them.

crowie
4th August 2014, 10:08 PM
The only fault, if you can call it that, is that the little pump gets hot pretty quickly. Much more than 30 min in one go and it's almost too hot to touch. I give it 15 minute bursts, then pull up the tail-stock with a padded disc and give the pump a break for a bit. Cuppa time.

I have a small 6" desktop fan on it now, which helps a lot, but in the longer run I'll either buy a bigger fan or a bigger pump. Probably the former.

I still haven't made any vacuum cups to go with it, either. Only the flat disc so far. I'll make them as I need them.

G'Day Steve,
Can I suggest that you check the "vacuum pump" manufacturers website for some technical spec's on running temperature & duty cycle ratings... They may have some "trouble shooting" charts that offer assistance...
Cheers, crowie

Hermit
4th August 2014, 10:35 PM
G'Day Steve,
Can I suggest that you check the "vacuum pump" manufacturers website for some technical spec's on running temperature & duty cycle ratings... They may have some "trouble shooting" charts that offer assistance...
Cheers, crowie

Hi Pete. This is only a cheap, no-name, Chinese pump, so unfortunately no website to check out.

Still, the reason it runs hot is that these pumps are only intended to run for short periods, while evacuating an air-conditioning unit. It's quite normal, from what I've seen and read, for them to get hot when used continuously. A decent fan will cure that.

The pump itself is oil-filled and doesn't get hot too quickly, either, just the motor.

Generally, only one or two 15 minute sessions are needed to finish the bottom of most things, too, so it's not much of a worry. Just a bit of turning on the foot, then sanding.

starr
27th March 2017, 12:32 PM
I was wondering how effective the silicon vacuum hose was, given that it doesn't look like it is reinforced.

I just bought the fittings to put my system together but they didn't have any hose and I have been having trouble finding it on the web, other than in the US, where they want two arms and a leg for postage.

Hermit
27th March 2017, 02:00 PM
I was wondering how effective the silicon vacuum hose was, given that it doesn't look like it is reinforced.

I just bought the fittings to put my system together but they didn't have any hose and I have been having trouble finding it on the web, other than in the US, where they want two arms and a leg for postage.

It works well. I don't do any turning any more, but during the time I used it I never had any problems with the tube collapsing. One of it's intended purposes is vacuum connections. It's a very solid hose.

You clearly didn't look in the right places. Did you try eBay? I typed in "6mm silicon hose" and got immediate results.
($5.65 per metre with free delivery.)
Silicone Hose Silicon Vacuum Tube Tubing for Water Air Coolant Blue Black Lime (http://www.ebay.com.au/itm/Silicone-Hose-Silicon-Vacuum-Tube-Tubing-for-Water-Air-Coolant-Blue-Black-Lime-/281732946560?var=&hash=item4198979a80:m:mMOeAksiOgplf92W3Shyu1Q)

DaveTTC
27th March 2017, 03:37 PM
I tried a home made set up using a shop vac. Didnt seem too successful on small items

DaveTTC

Turning Wood into Art

Hermit
27th March 2017, 05:55 PM
I tried a home made set up using a shop vac. Didnt seem too successful on small items

DaveTTC

Turning Wood into Art
No, a shop vac can't pull a high enough vacuum. Even using a vacuum pump like mine, small items are a bit touch and go, and require a light touch. Small items don't have enough surface area for a tight grip.

Uncle Al
27th March 2017, 09:34 PM
Can't add anything to the discussion, but really great to see Hermit back on the forum.
Welcome back, I look forward to more of your posts.

Alan...

BobL
27th March 2017, 09:56 PM
Interesting thread, thanks for posting.

A few years ago I picked up two 40+ year old 14 cfm Leybold laboratory two stage vacuum pumps from a skip at work. These are serious lab pumps designed to run 24/7 for decades and while they are designed to run hot (up to 95ºC is normal) I have not seen it get that hot even running it overnight.

These pumps had been used on and off electron microscopes for around 20 years and then put into storage until a big clean up deemed them surplus to requirements.
They needed an oil change and it cost me $75 to get special vacuum oil from the US for them but I managed to service them both and I still have enough oil for a second service and the seemed to run great after that. These pumps are supposed to pull a vacuum of less than one millionth of an atmosphere but of course that depends on how good the sealing is and to get that requires Viton O-ring gaskets. Anyway the RRP of these when they were new in Was over $1000 and I sold one on gumtree for $500 and kept one but have had nothing serious to do with it until now :).

It will have to go on my back burner but it sounds like a good use for it. I have a MW lathe so should be able to make some the vacuum bits out of aluminium or steel.

Hermit
27th March 2017, 10:53 PM
Can't add anything to the discussion, but really great to see Hermit back on the forum.
Welcome back, I look forward to more of your posts.

Alan...
Thanks for the welcome, but I'm sort of only back temporarily Al, since I don't do any woodworking any more. I'll probably poke my head up from time to time though, if I feel that I have anything to contribute.

Hermit
27th March 2017, 10:56 PM
Interesting thread, thanks for posting.

A few years ago I picked up two 40+ year old 14 cfm Leybold laboratory two stage vacuum pumps from a skip at work. These are serious lab pumps designed to run 24/7 for decades and while they are designed to run hot (up to 95ºC is normal) I have not seen it get that hot even running it overnight.

These pumps had been used on and off electron microscopes for around 20 years and then put into storage until a big clean up deemed them surplus to requirements.
They needed an oil change and it cost me $75 to get special vacuum oil from the US for them but I managed to service them both and I still have enough oil for a second service and the seemed to run great after that. These pumps are supposed to pull a vacuum of less than one millionth of an atmosphere but of course that depends on how good the sealing is and to get that requires Viton O-ring gaskets. Anyway the RRP of these when they were new in Was over $1000 and I sold one on gumtree for $500 and kept one but have had nothing serious to do with it until now :).

It will have to go on my back burner but it sounds like a good use for it. I have a MW lathe so should be able to make some the vacuum bits out of aluminium or steel.

As long as they can pull more than about 15inHg, they should be fine Bob. My pump needed a specialised oil too, but I bought a bottle when I first built the vac chuck system, for top-ups. Not cheap, but only very occasional top-ups are needed.

Paul39
28th March 2017, 04:00 AM
Auto fuel hose for fuel injected cars should be stiff enough. It is made for over 100 pounds per square inch pressure.

Our big box construction supply stores have a section in plumbing with all kinds of hose. I don't know what AU has.

There is a clear plastic hose for hooking up ice makers in refrigerators. It has a reinforcing braid embedded.

Smaller diameter will be stiffer, you only need to flow enough to overcome leakage in the system.

Pressure washer hose, good for 3600 psi! Airless sprayer hose. A scrap piece free or cheap from a bad one.

Check Here: Adelaide Belt and HoseABH Home (http://www.beltandhose.com.au/)

Automotive Hose - Supercheap Auto (http://www.supercheapauto.com.au/store/fuel-exhaust/automotive-hose/1021571?page=1&pageSize=24&sort=-ProductSummaryViewsWeighted%2C-ProductSummaryViewsTotal)

Hermit
28th March 2017, 01:56 PM
Auto fuel hose for fuel injected cars should be stiff enough. It is made for over 100 pounds per square inch pressure.

Our big box construction supply stores have a section in plumbing with all kinds of hose. I don't know what AU has.

There is a clear plastic hose for hooking up ice makers in refrigerators. It has a reinforcing braid embedded.

Smaller diameter will be stiffer, you only need to flow enough to overcome leakage in the system.

Pressure washer hose, good for 3600 psi! Airless sprayer hose. A scrap piece free or cheap from a bad one.

Check Here: Adelaide Belt and HoseABH Home (http://www.beltandhose.com.au/)

Automotive Hose - Supercheap Auto (http://www.supercheapauto.com.au/store/fuel-exhaust/automotive-hose/1021571?page=1&pageSize=24&sort=-ProductSummaryViewsWeighted%2C-ProductSummaryViewsTotal)

That silicon tubing that I used is pretty good Paul, and strong. I can't even begin to pinch it off between fingers and thumb, and it shows no signs of collapsing even under full vacuum. Since it's for vacuum and not internal pressure, reinforcing isn't necessary.

BlackbuttWA
30th March 2017, 12:58 PM
Steve. Very good plans & description of methods used.
I am watching with interest. I am off for a few weeks but will get into it when we get back.
My lathe has a different head stock so I will need to adjust as necessary.
Several guys at our club have similar set ups & it seems that the consensus is that the timber face plate with the rubber facing is better with a slight concave face.
This seems to help with centering & holding the project.
HTH
Col

Hermit
30th March 2017, 01:07 PM
Several guys at our club have similar set ups & it seems that the consensus is that the timber face plate with the rubber facing is better with a slight concave face.
This seems to help with centering & holding the project.
HTH
Col
That would definitely help when gripping items with a flat surface, but the flat faceplate is fine for finishing the bottom of bowls. I don't think that centring would be any easier with a concave faceplate though. The same process would still be necessary.

Edit: Having said that, a range of vacuum chucks is best, including some with a cup shape, so one with a concave surface would complete the set. For the bowls and the lidded boxes I made, though, the flat plate was fine. I had planned to make more chuck fittings, when they were called for, but gave up woodworking before I ever had the need for more.

N.B. This is a very old thread now, from mid 2014.

Sturdee
30th March 2017, 04:03 PM
N.B. This is a very old thread now, from mid 2014.

But only a very few threads, like this one, is like a good wine that improves with age.:U

BTW good to hear from you Steve, we've missed you on the forum.

Peter.

serjo
23rd March 2019, 06:32 PM
Hi,

@ Steve and all the others who build out this thread, thank you very much.
I have found a lot of solutions and especially good tips to prevent damage to the vacuum pump and also to prevent UFO's.:2tsup:

kind regards
Jos
Belgium:)