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Forum topic by Done posted 01-10-2017 05:56 PM 2737 views 0 times favorited 58 replies Add to Favorites Watch
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Done

34 posts in 44 days


01-10-2017 05:56 PM

Topic tags/keywords: done

Done

-- Done


58 replies so far

View Redoak49's profile

Redoak49

2078 posts in 1495 days


#1 posted 01-10-2017 06:53 PM

Yours is an interesting design. There are several out there at woodgears.ca

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Kazooman

662 posts in 1459 days


#2 posted 01-10-2017 07:07 PM

You will need to design in some good dust collection. Also, what are you planning to use for the drum? Sanding generates a lot of heat and that leads to burning the piece if you are not careful. The commercial models tend to have hollow aluminum drums that can bleed off the heat well. Supermax and Jet both claim that their drums are “self cooling” other manufacturers probably do the same. I take this to mean that the internal components of the drum are designed to create a flow of air through the drum to disappate heat.

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Done

34 posts in 44 days


#3 posted 01-10-2017 08:01 PM

I do see a lot of the sanders commercially available use the hollow aluminum drum, issue with this is making the drum. I have a lathe large enough to make it out of solid aluminum, but that would be far too heavy. So I was going to do as most I see do and that is laminate many layers of wood and turn it down to the diameter I desire. Should work out fine.

-- Done

View eflanders's profile

eflanders

118 posts in 1357 days


#4 posted 01-10-2017 08:07 PM

I’m going to undertake a similar project soon myself. In my research it appears to me that you may be underpowered for the drum. Many of the commercially made sanders of the width you are proposing use 3-5 hp motors.

I am hoping to use a former treadmill as the conveyor on my build. I hope it works… I will be watching your progress on this! Good luck!

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Redoak49

2078 posts in 1495 days


#5 posted 01-10-2017 08:24 PM

Shipwright made one using a Shopsmith to power it. He posted about it on LJ.

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William Shelley

193 posts in 976 days


#6 posted 01-10-2017 08:25 PM

Out of curiosity, has anyone designed drum sanders that have a perforated hollow drum to which dust collection can be hooked up to?

Splinter’s comment made me think that if you use a piece of hollow tube as a drum, it should be easy to drill a precise pattern of holes (for balance) and then make a template with “punches” poking up that you can roll the drum across with the sandpaper already on it to punch the holes in the paper.

-- Woodworking from an engineer's perspective

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Done

34 posts in 44 days


#7 posted 01-10-2017 09:31 PM

Great thought, but… I would have to say that the centrifugal forces of the drum spinning at 1700rpm would not allow dust to be sucked into the drum unless you had a monster vacuum pump. A bit of wood dust may not weigh too much but spinning that fast would have a lot of outward force.

-- Done

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Done

34 posts in 44 days


#8 posted 01-10-2017 09:33 PM

Also about the motor size, I took that into consideration when I chose the motor. I am using a 3450rpm motor so gearing it down to spin at 1700rpm will give me the torque I will need to run.

-- Done

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eflanders

118 posts in 1357 days


#9 posted 01-10-2017 10:08 PM

What are the 2 aluminum pieces for that are on either side of the sanding drum drive motor? I assume it’s some sort of motor mount, but then how will you adjust belt tension? You could make a vented drum by drilling holes equidistant around the drum and equidistant from the shafts as you make each drum segment but I would guess that these holes might cause the drum to flex some while under load. The flex issue is something other builders have mentioned in their builds. All have suggested using a minimum shaft diameter of 1” or greater for both drum and for the material hold-down rollers. I see your design so far does not include material hold-downs yet… Are you thinking of adding them? FYI On my old Delta 13” planer the shafts are all 1-1/4” diameter.

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Done

34 posts in 44 days


#10 posted 01-11-2017 12:08 AM

Yes the two aluminum plates around the motor are the mounts. The motor I had lying around is from an industrial impeller pump so the only mounting holes are on the face flange. The belt and pulley were quick, two minute, strictly pictorial parts I threw in there to show where the drive will be. I have not chosen the actual pulley sizes yet but will hopefully tomorrow while I’m at work (I mean I will be diligently working on work related stuff). But the actual system will utilize a positive motor mount location and a constant tension idler on the slack side. This will increase belt life and reduce vibration. I use to design commercial lawn equipment before my current job so I have a bunch of belt drive components kickin around. As far as hold downs, I have not yet designed those in yet. Also the shafts are 1.00” diameter.

-- Done

View Tooch's profile

Tooch

1443 posts in 1383 days


#11 posted 01-11-2017 11:10 AM

Adam/Oliva,

The design looks great. I’m assuming you decided to go with a manual feed? I’m not real familiar with that type of design, but have you giving consideration to any anti-kickback fingers?

Also, if you are going to document your build, you may want to consider creating a “series” in the Blog section rather than the forum post. The pages are all connected (near the top- part 1, part 2, etc.) so that people can follow along easily over the course of the build. You can see an example if you check out my Miter Saw table build, here

-- "Well, the world needs ditch-diggers too..." - Judge Smails

View ArtMann's profile

ArtMann

180 posts in 323 days


#12 posted 01-11-2017 07:22 PM

Horsepower is what defines the speed at which a machine does work – not torque. You can adjust the torque all you want but if you want to get any actual work done, you need a bigger motor. I know because I already own two commercially designed drum sanders with considerably more horsepower and they are slow. If a feed rate of 3 or 4 inches per minute or dozens of trips through the sander is acceptable then you are in good shape. If you use a 5 or 6 inch drum rather than the more common 4 inch diameter drum, you are going to lose all that powerful torque you created by using dissimilar pulley sizes. Stalling will be a real problem.

I agree with another poster that if you don’t have infeed and outfeed rollers to hold the work piece down, you are not going to be able to prevent snipe. You might be able to help a little by standing there and supporting the work piece during the time it is in contact with the drum.

If you use 80 or 120 grit paper on the drum and use 220 grit for the belt, then you are going to have a very hard time getting the conveyor to pull the work piece through the machine. Commercial machines that I am aware of utilize a 60 or 80 grit belt. It doesn’t damage the work piece because there won’t be any slip.

Auto feed is always good and will produce more consistent results but it requires you spend more money and development time to get it to work. You are going to be standing at the machine and cranking the handle a long time if you try to use a 1 horsepower motor to sand anything wider than a few inches.

I don’t see any gussets or other structures to prevent the drum head from racking from side to side. Your support pillars a don’t look big enough. What is going to keep the jack screws perpendicular to the belt?

I hate to be so critical of your design but I have considerable experience in the tool and processing engineering field as well as 40 years as a woodworker. I have serious doubts about the design as it now stands and would hate for you to spend a lot of time and money on a machine that won’t do the job for you.

In the end, I don’t think you will save any money at all building a drum sander unless you count your time as worthless – even if most the materials are salvage. It is going to take a lot longer than you think to get the machine debugged and working. If you simply enjoy experimenting with home made machines as a hobby, then that is its own reward.

At the very least, you should carefully study the designs of commercial machines as well as the successful designs of people who have actually built them. Stumpy Nubbs is a member of this forum and he has an interesting and unique design that I like but haven’t built.

View Done's profile

Done

34 posts in 44 days


#13 posted 01-11-2017 07:37 PM

Just gonna completely disregard that last comment. Apparently no real background or experience involved. But real good at stroking those keys.
Do you know the calculation for horsepower?
Here is it for you:

Secondly, it’s 3/4” aluminum and the attachment method of the drum prevents racking. People make these all day long out of 3/4” plywood!! Do you know anything?
Next yes, while I am fooling around in my shop, it is freeeeeeeeee!!! I do it for fun, not to make money. That’s why I have a real (engineer) job! And if you would have read a bit, the majority of parts and materials are leftovers from other projects or from dumpster diving at work. So I’m going to go with it will be much less $$!

-- Done

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Done

34 posts in 44 days


#14 posted 01-11-2017 08:58 PM

Hahaha. Just noticed something else wrong with ArtMann’s comically uneducated comment while reading it to my wife so she could get a chuckle as well! You have 2 commercially made drum sanders and they are feeding in inches per minute??! You need your money back!! Units are measured in SFM. Surface FEET per minute.

-- Done

View Dugbug's profile

Dugbug

5 posts in 923 days


#15 posted 01-11-2017 09:11 PM

I like your design, but have noticed a lot of shop built sanders seem to have short outfeed tables.
I’m not saying yours does but I wish I’d have made my table a little longer. A three foot long board will over hang a lot and may tilt the last part of the board up under the sandpaper. Just telling from my own experience. Good luck with the project.

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