LumberJocks

Drum sander surface speed

  • Advertise with us

« back to Power Tools, Hardware and Accessories forum

Forum topic by d_sinsley posted 08-15-2019 01:09 AM 263 views 0 times favorited 10 replies Add to Favorites Watch
View d_sinsley's profile

d_sinsley

21 posts in 10 days


08-15-2019 01:09 AM

Hi guys/gals, new here and I know this topic has been tossed around a lot but I am looking for specific information that I am really not finding an answer to. I am building a thickness/surface sander. I have the mechanics all worked out and the thing almost built but now I am second guessing my drum diameter. Here’s what I am working with. I have a 2hp motor that spins at 3450 RPM and has a 1.5” vbelt pulley (measured at the bottom of the v). I have a stack of 4 pulleys that are 2.5” on the big end and 1.5” on the little end. I don’t recall the in between sizes off the top of my head because I have only ever considered the larger pulley. I have already made up a drum using 3.5” X 3/4” plywood discs and figure by the time its sanded true will make a 3” drum. I am afraid after doing some reading that it is too small. I also have a piece of 4” C900 PVC water pipe (the stuff they use in the street not the stuff you use in your home) which has just shy of a 5” diameter. When sanded true I believe I should have about a 4.75” drum. I can make this up relatively easy.

Here is my question. I know where I can go to do the calculations for both RPM and surface speed per minute. What should be my target surface speed per minute? Where I am getting confused is everyone says a bigger drum is better but that also increases surface speed and I thought sanding need to be done at a slower speed to reduce heat and wear, am I wrong on this? As Drum size increases for a given RPM the faster the surface speed. this would tell me that my larger drum that I am leaning to will be sanding faster than my small one. With my current set up I have a drum RPM of 2070 at its slowest. The drum surface speed of the 3” drum then would be 1627 SFM. Whereas, a 4.75” drum would be 2576 SFM.

Now if I am misunderstanding the desire to have a slower surface speed and that faster is actually better then I also have the option of turning faster RPMS with the smaller pulleys in the stack. So my question is two fold, is a larger drum indeed better than a small one and what should my target surface speed be?


10 replies so far

View d_sinsley's profile

d_sinsley

21 posts in 10 days


#1 posted 08-15-2019 01:48 PM

So I may have answered my own questions with further searches here. And with a double check of what I have. So my motor is 3450 but the pulley on it is 1 1/4” not 1 1/2” and the stack of pulleys I have has the two larger ones being 2 3/4” and 2 1/4”. so using those two sized pulleys I can achieve an RPM of 1568 or 1916 respectively. Making a 4 3/4” drum I will achieve surface speed of 1951 and 2384 respectively.

I should add here that I am making a 12” disc sander on the end of the shaft which of course will run at shaft speed.

I did see a post on here where it seemed a surface speed of between 2000-2300 is a good target for the drum and that most disc sanders run at shaft speed of a 1725RPM motor. So with a 2 3/4” pulley I am a little slow on both ends (1568 shaft/ 1951SFM drum) and on the 2 1/4” I am a little fast on both ends (1916 shaft/2384 drum). My uneducated first thought is slower is better to prevent things from heating up. So my natural tendency is to lean toward the largest pulley.

What your guys thoughts?

View HokieKen's profile

HokieKen

10437 posts in 1593 days


#2 posted 08-15-2019 01:58 PM

Sounds to me like you can easily tune your speeds by just changing out one or both belt pulleys. I would just finish the build and try it with the two pulleys you have. After using it for a while, you’ll have a good feel for whether or not one of those is good or if you need to try a size somewhere in between. Those speed guidelines are just that, guidelines. Just get some hands-on time with it and see what works for you and for the woods you’re using.

Just my $.02. Good luck with it! Make sure you post some pics of your build :-))

-- Kenny, SW VA, Go Hokies!!!

View d_sinsley's profile

d_sinsley

21 posts in 10 days


#3 posted 08-15-2019 02:46 PM

thanks Kenny,

I posted a blog post as an introduction and included where I am with the sander project. I could easily switch a pulley and if I need to that is what I will do. I am just trying to use what I have on hand and Figure since its a stack of pulleys it will be easy to do just as you say and try out both and see what is working best and if I need to change. Your response was more or less confirmation of what I was already thinking and that is what I was hoping for was confirmation.

View therealSteveN's profile

therealSteveN

3390 posts in 1029 days


#4 posted 08-15-2019 05:22 PM

My first and only wide belt sander is a https://www.supermaxtools.com/products/wood/19-38-drum-sander-71938-d/ I like it a lot, one of it’s best features for me is it has an adjustable belt feed rate. Look at the videos, pics, and whatnot to see it in use, no grabbing belts or anything, just turning a knob. It is easy. I know from lathes of the past, and drill presses of the here and now, I am less prone to change a belt speed, if what it is at, is OK. We all know Ok isn’t optimal. Every board I run through that belt sander I tweak the speed, just because it’s so darn easy.

I can work on tools to make them work, but I am not a tool mechanic, nor a designer, but I would look into a store bought sander with a variable speed unit, and see if that is something within your skill set. Because if it is, and you don’t do something like that????

-- Think safe, be safe

View HokieKen's profile

HokieKen

10437 posts in 1593 days


#5 posted 08-15-2019 05:28 PM

SteveN has a good point. If you can find a 3 phase motor at a reasonable price (which you can, I got a 2 hp Baldor off eBay for less than $100 shipped) you can add a ~$100 Variable Frequency Drive and have your speed adjustment with the turn of a knob. Would require a little more investment but might be worth it for the additional capability it would add to your sander. And you can probably sell your 2 hp single phase motor for close to enough to cover the cost of the motor and VFD. Single phase brings a higher price in the used market because it’s just more convenient for most home owners.

-- Kenny, SW VA, Go Hokies!!!

View d_sinsley's profile

d_sinsley

21 posts in 10 days


#6 posted 08-15-2019 05:50 PM

Guys I never even considered this. this is why I came here with my questions. I just so happen to have a brand new three phase motor that I picked up with a bunch of other stuff at an auction. I know it is 1725 RPM but for the life of me I can not remember how big it is I want to say its a 1 HP but not sure. I will have to look. Would a 1 HP motor be enough to run a sander. I would think so as long as I don’t try to take it all off in one pass.

As for the 2HP single phase motor I have another bucket list project that could use it.

View HokieKen's profile

HokieKen

10437 posts in 1593 days


#7 posted 08-15-2019 06:38 PM

I don’t really know if 1 hp would get the job done or not d. I’ve never used, let alone owned, a drum sander. I used a 2 hp to build my belt grinder and it has plenty of power and I grind steel on there and really lean into it sometimes with no bog down whatsoever. I don’t know how that compares to the load of a drum sander though. It’s less force being applied but it’s also being applied over a much larger area.

If you do use the 3ph motor for this or something else, myself and at least 3 other guys I know have used these VFDs run motors for grinders and lathes. For the money they’re great. You just have to be careful that you can enclose it somewhere to keep it away from getting dust in it.

-- Kenny, SW VA, Go Hokies!!!

View d_sinsley's profile

d_sinsley

21 posts in 10 days


#8 posted 08-19-2019 01:10 PM

Well unfortunately after looking at my 3 phase motor it is only a 1/2 horse motor. So at least for now I will be sticking with the 2hp single phase motor I currently have and control speed with the pulleys. I can always upgrade later should I need to. I really like the idea of putting on a VFD.

View PPK's profile

PPK

1476 posts in 1264 days


#9 posted 08-19-2019 05:25 PM

My 1.5Hp motor works great, and only bogs down if I’m doing something I should be.

Don’t sweat the speed calcs. I did all those with my build, and what I found in the end is that it is virtually impossible to overheat the drum and/or burn the wood when sanding IF you use velcro to attach the sand paper. I think this is the key. Steel drums where the sandpaper applies directly is where heat builds up. Wood drums with velcro heat up so minimally its negligent, in my experience.

When you build a drum sander that’s “manual feed” you can so easily control the feed rate. It seems like a negative to not have an automatic feeder, but I much prefer feeding manually. You can feel the pressure and react accordingly.

Here’s a link to the sander I built, in case it’s of any help. Of course there are many other blogs on here too that are very helpful.

https://www.lumberjocks.com/projects/252242

-- Pete

View d_sinsley's profile

d_sinsley

21 posts in 10 days


#10 posted 08-19-2019 06:43 PM

Thanks Pete. Thats a great looking sander. I like that you used plexi (lexan?) on the cover. Kinda an interesting idea might have to do that.

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com