Thread: my Drum Sander

Great job. I am sure you will get plenty of use for that!.
Well done

That's very functional. Strongly built.




Regards
Jack
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That looks fully sick. Good work!

Very nice.

How do you raise the bed? Do you shim it up or was there a mechanism that was not shown in the images?

plus which way does the drum spin? does it rip the timber out of your hands flinging it straight through? or do you have to really push it through (and then when you get to the last little bit it flings the timber back at you)?

Looks good.

Originally Posted by rod1949

. . . . plus which way does the drum spin? does it rip the timber out of your hands flinging it straight through? or do you have to really push it through (and then when you get to the last little bit it flings the timber back at you)?

I'd also like to know the answers to these.

Thanks

Hmm
thinking of making one of these but I need it 1000mm wide...
would there be issue (assuming I use 2HP motor)???

Originally Posted by BobL

Looks good.

I'd also like to know the answers to these.

Thanks

Take a look at the last 2 photo's, it looks like the table adjusts up and down via a hand screw.

Originally Posted by BobL

Looks good.

I'd also like to know the answers to these.

Thanks

Hello,

I can't answer for Paul but I have one very similar and here are some thoughts ................


On my sander it spins towards me - this means that 99.9% of all dust created is extracted immediately by the dust extractor and it doesnt foul the sandpaper.

If you spin it the other way I think there is more chance that the sandpaper becomes fouled with its own dust being ground into it and heated by friction ?

This does raise the issue of having it spit the wood back at your belly - I generally stand to one side to avoid this problem.

On my sander I can walk around the back and pull the timber through - its not a big deal - but a health and safety purist might not like it - keen to see comments from Paul and others on this.

The following ideas might work but would need some sort of risk analysis and comments from others would be helpful before trying them ............ by trying these thing we are abandoning the KISS principle ...................

Wouldn't be too difficult to use a wide sacrificial push stick for the last few inches.

Wouldnt be too difficult to build in a spring loaded or foot operated fence to prevent the sander from pushing the piece back into your belly - fence rises after back end of plank passes front of table - see comment above regarding standing to one side.

Wouldnt be difficult to build a little hook and pulley system under the table so that a hook or pegs of some sort poke up out of slots in the table the table behind the end of your plank and by turning a handle or pulling a chain towards you the last little bit of the plank goes through under the drum.

Would probably be a complex and difficult job to build a sandpaper conveyor running to carry the plank under the drum and out the other side - perhaps a hand cranked conveyor ? Anybody done this - am sure I have seen one somewhere ?

All of the above become irrelevant if you are prepared to stand to one side and stop the machine pull the plank out and feed in the other end first - I dont know how sensible that would be ?




Regards

Bill

This looks like a nice bit of engineering.
Have you tested it out yet ?
I would say deninitely that the drum needs to rotate towards you and you need some spring-loaded rollers to provide some downforce on the work piece especially on small or lightweight work pieces.

Originally Posted by Pauls321

Hi all, I've had a thread going on in another section here, titled "pulleys". The thread was when I was in the process of starting to build my own drum sander. Just wanted to share the final photos of the drum sander again. I am very impressed with the final result. Any other questions might be answered in the aforementioned "thread". Sorry about any glare in the photos, its a very hot day here today.

Regards, Paul

Originally Posted by steamingbill

Hello,
I can't answer for Paul but I have one very similar and here are some thoughts ................
On my sander it spins towards me - this means that 99.9% of all dust created is extracted immediately by the dust extractor and it doesnt foul the sandpaper.

Is this a visual determination or have you done a dust particle count measurement?
If not, it is not possible to say how much dust is collected.
Sanders make very fine dust and as much as half can be invisible which is the stuff that is likely to cause health problems.

Paul, nice job on the machine but I don't know why you ran a 4" flexy to the sander and then restricted down to a ~2" duct?

A 4" flexy can draw ~350 CFM from a 2HP DC or bigger, but a short 2" restriction will immediately throttle the flow down to about 120 CFM.
As I said above, sanders make a lot of invisible dust and 120 CFM is far to low to collect this dust especially at the edges of the sander.
I see you are using a 1HP single bag unit which at most (with a clean bag) will pull about 250 CFM but I would still recommend enlarging the port in the top of the sander to a full 4" and connecting the flexy direct to that.
BTW, when used on a sander the bag on those one bag DCs clogs very quickly and needs to be cleaned very regularly to maintain a reasonable flow - it may look like the flow is OK but most operators have no idea that their bags are clogged - they thing their flow is just fine and when I measure it, it can be as low as half the optimum flow.

Ideally 1000 CFM is needed to be sure of grabbing as much of the the fine dust as possible.
Where only 4" ducting is being used I usually recommend 2 x 4" ducts are used on a sander
the best place to vents DCs are of course outside a shed

Originally Posted by BobL

Is this a visual determination or have you done a dust particle count measurement?
If not, it is not possible to say how much dust is collected.
Sanders make very fine dust and as much as half can be invisible which is the stuff that is likely to cause health problems.

Hey Bob,

Thanks for the comments - thats interesting - where do I go to learn more please ?

Agreed 99.9% is an estimate and not a measurement.

Am a bit puzzled - If I run the sander for an hour and there is very little dust on the table when I have finished surely that means that I have got most of the dust.

I could empty the dust bag and weigh what I win in the bag and add it to the tiny amount that is left on the table but I dont know how to measure the invisible stuff. I would assume anything to small to see would go straight up the 4" hose ?

How about this ? - Weigh the captured dust - weigh the timber before and after and whatever is missing has escaped into the air. Will give it a go and see what happens. Suspect it will be below the level of accuracy that I can achieve at home. Maybe a lab test would determine this - will do some googling.

Its mentioned in your post "as much as half can be invisible" does this invisible dust manage to somehow resist being sucked up by the dust extractor ? - given that I have a 4" extractor hose right on top of the drum I think its unlikely, but am concerned enough to learn more if I can.

If its invisible it must be tiny, how would it avoid being sucked up by the dust extractor ?

Would be very grateful if you could point me towards some relevant web pages or Australian standards that would help me to understand this better.

I will watch more carefully the next time I use it - if any visible dust escapes then the invisible dust could also be escaping - perhaps I could put curtains of some sort between the table and the bottom of the dust extractor ? Is that a standard practice to control the very fine dust ? Would have to be adjustable to avoid getting tangled with the drum but that is achievable.

Am off to Google fine wood dust and drum sanders

Regards

Bill

Originally Posted by steamingbill

Am a bit puzzled - If I run the sander for an hour and there is very little dust on the table when I have finished surely that means that I have got most of the dust.

Unfortunately not so, fine invisible dust act more like like a gas than sawdust. The motor and the sanding action creates a fair amount of heat which has to be dissipated somewhere and that will be mainly into the air. The very fine dust generated by the sander will ride on the air currents generated by the rotating drum, and the warm air currents rising up from a sander, up to and along the ceiling and eventually fill the shed. If there is limited or no ventilation over the next day or so this dust will settle out everywhere inside your shed. To determine how much dust a sander leaks one would have to scrupulously clean a shed and then run the sander and the scrupulously clean the shed again. The question then becomes what to clean with? A new (old ones can pump out more dust than they suck up) premium vacuum with a HEPA filter would be as good as you could get. Weighing the HEPA filter before and after would be one way to assess this but this would assume that nothing else in a shed is making dust whereas all exposed wood (especially MDF), metal, cloth, skin, exposed concrete and even painted surfaces make dust. It's a test that would need to be done in a plastic coated ultra clean lab with nothing else in it.

I could empty the dust bag and weigh what I win in the bag and add it to the tiny amount that is left on the table but I dont know how to measure the invisible stuff. I would assume anything to small to see would go straight up the 4" hose ?

It will depend on how seasoned the bags are. When the bags are clean the dust collector will have better flow and so capture more dust at source but then the bag itself may only retain about ~75% of fine dust - the rest will pass straight thru it to also contaminate the shed. When the bag is seasoned (ie has been collecting dust for some time) the bag will retain more dust (as much as ~ 95% of the fine dust the DC collects) but then the flow will be lower at source and so less will be collected at source. This is the reason why cleaning bags often and locating a DC outside is increasingly being employed to reduce dust levels in sheds.

How about this ? - Weigh the captured dust - weigh the timber before and after and whatever is missing has escaped into the air. Will give it a go and see what happens. Suspect it will be below the level of accuracy that I can achieve at home.

Its mentioned in your post "as much as half can be invisible" does this invisible dust manage to somehow resist being sucked up by the dust extractor ? - given that I have a 4" extractor hose right on top of the drum I think its unlikely, but am concerned enough to learn more if I can.

Ah ha - now you are getting to the nub of the problem - you are talking "mass" whereas we should be talking numbers of particles of different sizes. The big particles might make up 99% of the mass but these are not a problem and health-wise can be almost ignored. The invisible dust is much more likely to do harm and may indeed only be 1% of the mass of the dust but make up 50% of the particles which can be the case with MDF.

About the only practical way the amount of dust escaping from these machines can be checked is using a particle counter - which is what I have been reporting on in the dust forum.

If its invisible it must be tiny, how would it avoid being sucked up by the dust extractor ?

It is tiny - its in the low micron range. To extract these at source requires the same approach as used for gasses. It may sound crude but invisible dust is like a fart - the only way to stop it escaping is a large volume air flow at source. The other approach is what I call the "car approach" i.e. let it escape but use very good shed ventilation ie large roll up doors - large windows and extractor fans to replace the shed air as quickly as possible.

If you have a few days to spend look up someone called Bill Pentz and look at what he says about this issue. His recommendation is 800 - 1000 cfm of extraction at source. This requires a 2HP or bigger DC that uses 6" ducting or bigger - it is simple not possible to do this with a 1HP DC and 4" ducting - read Bill Pentz site on this.

Retro fitting to existing sheds and machinery is expensive - but people thinking about building sheds should serious factor DC into shed design and cost just like the would a roof or a door - it's better to lose some square m of shed and spend that on 6" ducting and proper electrical wiring to run a bigger DC than have no DC and a bigger shed. I am somewhat bewildered when people spend many thousands on their sheds and tens of thousands on machinery and tools and then say all they can afford is a $200 DC. It's a bit like buying a more expensive car and then not having enough money left for the insurance.

Would be very grateful if you could point me towards some relevant web pages or Australian standards that would help me to understand this better.

As well as Bill Pentz's site we have a comprehensive dust forum on this site - plenty of stuff in there about dust extraction. You will see lots of posts about how I test DC systems and processes etc.
The Australian standards (5 mg/m^3 for softwoods and 1 mg/m^3 for hardwood) are the same as the US and are the old European standards expressed which are now known to be inadequate but even tho current standards are illuminating. It only takes a quarter thimble full of hardwood dust to contaminate the air in a 6 x 4 m shed to the Australian standards levels of 1mg/m^3 . Check this post here to get a visual idea of this and discussion of what this means in a shed. The new standard for MDF is 0.3 mg/m^3 - you can scale that to a thimble and a shed for yourself.
The European standards are particle size specific and much more stringent. All the standards assume you are working 40 hours a week in this environment which is how most weekend warriors get away with it but I increasingly see a lot or especially retired folks spending a lot of time in dust sheds.

I will watch more carefully the next time I use it - if any visible dust escapes then the invisible dust could also be escaping

Visual evidence is not a good guide. In fact some of the very best dust extraction systems may even let some larger visually evident chips of sawdust escape because these chips have the momentum to overcome the air speeds generated by the C system. While it is a good idea to use high air speed it's flow (cubic ft per minute) that captures fine dust. Bill Pentz has also done a lot of testing and recommends 1000 CFM at source to be sure of grabbing fine dust from big machines. Most wood workers do not under

perhaps I could put curtains of some sort between the table and the bottom of the dust extractor ? Is that a standard practice to control the very fine dust ? Would have to be adjustable to avoid getting tangled with the drum but that is achievable.

This is a very good idea. CNC users use thin lines of longish bristles as curtains. One source of these are truckies mud guard splash guards - unfortunately these are not cheap, also they block vision but they are supposed to work well. I will eventually be installing some of these on my table saw guard and testing these curtains so I can report back on how effective they are.

If you do any more testing I suggest you start a new thread in the Dust form as it is better suited to that forum than this one.

Thanks Bob,

This dust business is far more complicated than I thought.

Bill