Thread: Improving machine cabinet dust ports

Bobl you making any more BMHs anytime soon?....

Bob, Was wanting your thoughts on drum sander modifications. Supermax 25-50 has a single 100mm port on top that is 60-70% taken up by grating across the port. I'm thinking of creating a replacement lid to go on the sander (not voiding warranty this way as the stock lid is removable with 4 screws). Would a single 150mm port in the center be better than say, two spread out 125mm ports? Assuming 150mm pvc duct all the way from the collector. The manual is calling for at least 600cfm through that little port..... hmmm... Cheers.
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Originally Posted by hurcorh

Would a single 150mm port in the center be better than say, two spread out 125mm ports? Assuming 150mm pvc duct all the way from the collector. The manual is calling for at least 600cfm through that little port..... hmmm... Cheers.

Two x 125 mm ports will be better than 1 x 6" port. The killer with these sanders is the gap where the wood passes through is too small. Its not as bad with narrow pieces but when the wood is approaching the width of the gap dust collection becomes pretty poor. What is needed to maintain flow are some holes in the sides of the body of the sander like this. But of course no one wants to be doing that to a new machine and you don't want to reduce its vertical strength rigidity

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On the mens shed sander where the drums are supported at both ends we were able to improve things by replacing the removable side panels like this but this one only has 2 x 100 mm ports and like yours the ports would benefit from being at least 125 mm - sigh yet another mod to get round to.

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Bob instead of venting the casting could the hood just be made bigger and cover the outside of the casting with say an inch gap front and back? I think that would pull any dust not removed from the inside of the casting? Or would it shortcut the airflow. The critters weren't made for dust capture.

Pete

Originally Posted by QC Inspector

Bob instead of venting the casting could the hood just be made bigger and cover the outside of the casting with say an inch gap front and back? I think that would pull any dust not removed from the inside of the casting?

That would deal with the fine dust.

The critters weren't made for dust capture.

I agree, an issue with drum sanders is that because they don't have enough air flow close to the drums where the dust is generated a considerable amount of coarse and medium/fine dust is deposited onto the work. Once deposited it is very difficult to pick up and ends up interfering with the sanding - some form of dust clearing mechanism like pulses of compressed air could be considered to re-suspend this dust which an additional hooded cover might be able to pick.

Jeremy, are the dimensions of the conduit (ID & OD) the same as sewer and drain pipe?

Originally Posted by BobL

On the mens shed sander where the drums are supported at both ends we were able to improve things by replacing the removable side panels like this but this one only has 2 x 100 mm ports and like yours the ports would benefit from being at least 125 mm - sigh yet another mod to get round to.

IMG_1916.jpg

How does the men's shed go about cleaning the drums with this setup? ie to minimise burning/build up on the drums? would imagine with the rigid pvc that would be a real pain to remove and setup each time you wanted to run an abrasive stick over the drums.

Originally Posted by tonzeyd

How does the men's shed go about cleaning the drums with this setup? ie to minimise burning/build up on the drums? would imagine with the rigid pvc that would be a real pain to remove and setup each time you wanted to run an abrasive stick over the drums.

The PVC was not made rigid back to the trunk line - above the Y junction there is about 1m of 6" flex and the Y junction can just be lifted off and left dangling from the flex. It's not that good at picking up the dust that ends up on the conveyor belt and falls off onto the floor as it goes around the roller. Someone else did install a length of slotted PVC that catches the stuff falling off the belt and connects to a shop vac and that helps but is still not 100% effective. I haven't been to the mens shed for some time and as I did not finish hooking up all their machines to the DC system I'm not sure how they are getting on dust wise. I do still get their newsletter and note an article on cleaning up wood dust after using machinery and it looks like the belt sander still remains a problem.

Well, here's my first try. 150 mm. Got the same crimp as BobL did on his first. I suspect that the temp. was too hot near the problem area compared to the flare end, but I may have this backwards. The temp. was generally around 95º. Or maybe I was too aggressive pushing in. Any thoughts, guys?

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Originally Posted by blackhorse16a

Well, here's my first try. 150 mm. Got the same crimp as BobL did on his first. I suspect that the temp. was too hot near the problem area compared to the flare end, but I may have this backwards. The temp. was generally around 95º. Or maybe I was too aggressive pushing in. Any thoughts, guys?

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Yep looks familiar. 95ºC is about right for where the ruck is but too low for the very end of the pipe which I usual have around 105-110ºC

The temperature of the pipe just prior to forming should be progressively less from the end - so, 105-10 at the flared end - 95 at the ruck point (say 2" for the end) and <70 at the 4" mark. Once the fare starts its a matter of playing the heat gun back and forth along the pipe as the lathe turns spending slightly longer at the flared end as it has to stretch much further than the rest. The more flare that develops the harder it has to be pushed. I smear so light machine oil or paste way on the former to help the process along. Once the required flare has been reached I keep applying heat from a little further back for about 30s to allow the whole thing to settle and helps reduces shrinkage when the tailstock pressure is removed.

I found it easier to for the hoods using ~150 mm long pieces of ducting so that leaves a decent length of cool solid still hard end of pipe for the tailstock to push on and to fit into couplers etc . I usually cut any excess off the unflared section with a bandsaw.

Thanks for the response, Bob. I had visions of charred PVC dancing in my head and probably went too low on the temp at the flare. I wasn't too displeased as the rest of the process went pretty much as you had described. I'll try again soon. Even this one is better than no flare at all. Since wood is such a terrible conductor, I was thinking about pre-warming the inside of the PVC up to maybe 75º.

Originally Posted by blackhorse16a

Thanks for the response, Bob. I had visions of charred PVC dancing in my head and probably went too low on the temp at the flare. I wasn't too displeased as the rest of the process went pretty much as you had described. I'll try again soon. Even this one is better than no flare at all. Since wood is such a terrible conductor, I was thinking about pre-warming the inside of the PVC up to maybe 75º.

Yep even that one will be better than no flare but if you keep persisting is should work. I had about 5 goes before I got what I was after although some were deliberate fails just to see what would happen.

Yes you can preheat the inside of the PVC - I did that a few times by placing the on the former and with the tailstock held back and the lathe turning slowly played the heat gun on the inside of the pipe protruding from the former. Then flipped the pipe over and started the full on process.

Now I just preheat the former so the flared end is around 100º and its about 80º further back - this takes a while but is well worth doing.

You will get some notice of overheating as the PVC will stay to go glossy and then it will start to go brown - this is bad because it now actually breaking down but it has to be quite hot to do that.

Originally Posted by BobL

Yes you can preheat the inside of the PVC - I did that a few times by placing the on the former and with the tailstock held back and the lathe turning slowly played the heat gun on the inside of the pipe protruding from the former. Then flipped the pipe over and started the full on process.

Bob, how do you think it would go if you dipped the pipe in boiling water or even hot oil for a short while before putting it on the former?

Originally Posted by doug3030

Bob, how do you think it would go if you dipped the pipe in boiling water or even hot oil for a short while before putting it on the former?

Hot oil is messy, but I reckon boiling water would be a goer as it would be quicker than a hot air gun - I have thought about doing that , I didn't like the idea of dripping water onto the CI lathe bed although once could of course wipe it off before hand.. With boiling water the stub end of PVC would need to be dunked in and out of the water to get the spread of temperature needed (you don't want it uniform or it can ruck) and by the time you get the PVC out of the water and onto the former etc the PVC will probably lose 5ºC, (more if the former is not preheated) and further hot air treatment will still be needed to get it to 105 - 110º. I recently bought myself a 10L SS pot for metal bluing etc - might give it a go next time.