Best grit for drum sander?

[joel]

Now that the stress of uni exams is over I've finally managed to put my brand new second hand Performax 16-32 together (dismantled for transport).

I still have to get the drum parallel with the table, and while I'm working on that I thought it'd be a good idea to get some sandpaper for it. But what is the best grit/type of paper to use on this machine for the various guitar making tasks I'll be using it for, thicknessing top, back, sides, braces, and a whole host of other things I probably haven't thought of yet.

Would something like this be suitable, and what grit is the best all-rounder? http://www.activeabrasives.com.au/home.php?cat=279

[Kim]

80 grit.

[Kim]

Ok, ok, I think that 80 grit is best because ANYTHING finer will heat up clog and burn on most wood. For really oily wood like Bocote, Cocobolo etc, you should really get the worst of it down with a Wagner Safe-T-Planer and then finish with the drum but you 'can' use 36 grit to hog off and then finish with 80 grit. Be careful if doing this because 36 grit runs deep, go too far and you will ruin the set. For spruce you can drop down to 120 grit however for the effort involved in changing belts, I find it is easier to finish on the machine just a tad thicker with 80 and then hand sand this softwood for about a minute on the bench.

It is also important to remember to sand where ever possible at an angle to the grain when infeeding, this will also help prevent clogging and burning and you can then finish off with the grain. Equally as important is very good dust extraction. You should aim to have as much air pulling through the hood as you can get or your belt will clog and burn.

The secret to operating these machines successfully is for the user to first come to terms with the fact that they are NOT a thicknesser. I know that we all use them as such however if you maintain in your mind that you are doing something that the machine is not designed to do when you are thicknessing, then you stand a better chance of keeping your patients throughout the process and avoiding the temptation to take anything but VERY light multiple passes on each setting. Do the job any other way and your belt will clog and burn.

Hope that helps.

Cheers

Kim

[Bob Connor]

80 grit is what is usually on our sander.

We have 40 grit for hoarking off a heap of wood but as Kim says it leaves deep scratches that take forever to sand out of hardwood.

I use 240 grit for soundboards. Particularly when they have the rosette installed. I've sanded a couple with 80 grit which left marks in the hard wood of the rosette. When trying to sand them out with the ROS, it creates dips in the spruce (or Cedar) around the hard rosette material.

Just gives me a better finished result.

Mind you the 240 grit usually gets left on the sander and one of us will poke some hardwood through it which usually wrecks it pretty quickly.

[James Mc]

A sharp plane is a beautiful thing… shavings are much easier to deal with than dust.

On a related but unrelated subject, I was chasing a good size piece of cloth-backed sandpaper to glue down as a large flat sanding surface. As per usual when living in a regional town, you just can’t find what you want and when you do it costs an arm and a leg. I ended up finding some floor sanding belts on trusty old Ebay. I got five 60 and five 100 grit heavy-duty cloth backed belts 300mm wide x 800mm long for about $35 (including postage, which was more than the belt). I cut one through the join and it was perfect for what I was after.

I’m not sure how $3.50 each compares with what you would pay in the big smoke, but they were better value and quality than anything I could find here. So if any of you other guys living out in the boonies has a need for something like this, then just search for ‘floor sanding belts’ on Ebay.

Cheers
James

[Taffy Evans]

I do as per Kims post, and also sand on the angle and finish up straight. I get close to the sanding stage with my thicknesser. I'm in no rush most of the time so I use many shallow passes on both machines.

[Allen]

I only bother with installing 80 grit. I make sure that I've got just a bit of wiggle room when sanding the top, because they will loose dimension quick smart when you start to finish sand. 80 grit marks are easy to get out with finer grade of paper by hand or with the ROS. Not so when you leave 60 or coarser.

And as the others said. If you try and use finer paper on anything oily or resinous, you're going to ruin that paper in no time.

[Kim]

Anyone here tried sanding Bocote? I have one set which is like sanding wax! I have sanded a bit of Cocobolo and that is oily wood but Bocote leaves it for dead, it will clog 36 grit if you don't go really careful. Thank goodness for the Wagner finger grinder is all I can say.

Cheers

Kim

[joel]

Yeah, I've got a Wagner Safe-T-Planer. Wonderful bit of kit. I've used it only on my back and sides. The back to take off a little thickness before glue-up, and almost to thickness on the sides.

I shouldn't have said thicknessing in my first post. But point well taken Kim. My plan for the drum sander is for finish (or close to finish) sanding most components. Or to clean up a rough surface so I can more accurately mark stuff out (like my neck blank that I will get started after the drummy is up and going). And to get the braces to final thickness.

I currently rough things to dimension with the Wagner or a hand plane.

So far, from reading everybodies posts, I want a smooth 80 grit or a course 240 I might get 80 grit for the drummy and a nice wide belt of 240 to make a big sanding board for getting any marks out.

[Kim]

Good plan Joel,

My advice is to also get some 120 grit as well to glue on the other side of your sanding board. This configuration gives you 120 to smooth things out after the 80 grit preformax, and when you flip the sanding board over, you have 240 grit to clean up the rosette without leaving a ridge, it works well.

I only used melamine for my boards as it will stay flat, is cheap, and it is easy to peel the old paper off when worn. Also you can easily clean up the old spray on contact glue with acetone (use gloves), and then your ready to go again using the same board with fresh paper and fresh spray on contact. By the way, no need to go too wide, half sheet is just fine to spread the load and I like to use the cloth backed stuff as it last for ages.

Cheers

Kim

[Stu]

I agree with loading your drummy up with 80 grit.

I've got a Twin drum sander using 80 grit on the entry drum , 120 grit on the finishing drum and I'm finding the 80 grit lasts a heck of a lot longer than the 120 grit.
In fact I haven't changed the 80 grit drum yet, whereas I've changed the 120 grit over at least 6 times since I got it earlier in the year.


I was surprised at how different the clog rates were between each
drum grit.

cheers, Stu

[Hesh1956]

80 grit for hard woods and 120 for soft woods and when I am too lazy to change it......

Remember that these drum sanders are not engineered or capable of hoarking off large amounts of material in a single pass. I never turn the crank more than 1/8th turn at once and putting it through again without touching the crank will often take off another .002 - .003ish of material.

I have some 36 grit for the native Olive that I have but beyond that 80 has handled every hard wood that I have ever built with.

[sebastiaan56]

I’m not sure how $3.50 each compares with what you would pay in the big smoke, but they were better value and quality than anything I could find here. So if any of you other guys living out in the boonies has a need for something like this, then just search for ‘floor sanding belts’ on Ebay.

Thats a good price James, better than retail in Sydney,