The use of drum sanders has become more and more common as the woodwork hobby industry has expanded into products like the end grain cutting board. The challenge for the woodworker is to find the right grit to get the job done without leaving too much work after the drum sander for the random orbital.
The cost of a roll of sandpaper can be high, and for the beginner and the novice it can be out of financial reach to begin with a large selection of grits. This article is designed to help choose the right starter grit for the task, without blowing the budget. When I bought my drum sander this question came up and I did end up getting the wrong grit, simply because I had no experience to work with. This article might help you avoid that mistake.
What Is The Best Grit For Drum Sanders?
The best grit is 80 grit. It allows the wood to be removed without excessive heat build up within the sanding drum and the paper. Excessive heat will shorten the life of the sandpaper and can cause problems over time with the running gear of the drum sander.
The answer above is useful for quick stock processing and will not give a final finish quality that a higher grit can deliver, however, every grit higher you progress to, the more you will rely on a quality dust extraction system to help out.
I now have a range of grits from 60 grit up to 320 grit and after 2 ½ years of regular use I can now comfortably speak with a little bit of authority.
What I know is these are the two biggest issues that you will face .
- Controlling Dust.
- Sandpaper Clogging.
The grade of grit does not matter if you cannot remove the dust as it is generated at the drum, and the only satisfactory method to achieve this is through vacuum lines connected to a mechanical air pump, either a centrifugal system or a venturi system.
These only operate at their best when kept at a satisfactory level of airflow and filtration; so allowing the filter side of the dust control to become blocked will limit the dust removal ability and end up with more heat at the drum and less productivity in the shop.
This is the result of not enough dust control and it happens with every grit. You might think that 60 grit will be fine because of the depth of the granules on the paper and it looks like it would clear itself, but because the grit is so aggressive the size of the dust particles build up far quicker and actually clog as fast if not faster than a higher grit.
There is no grit that can be used on a drum sander without dust extraction. A very beneficial helper that actually works is the cleaning eraser stick, in fact, I suggest you get a few and have one handy at the sander at all times. They are great for getting the most life from your sandpaper.
If you consider the two issues above, being dust extraction and paper clogging, you will see that the lack of one gives rise to the other, however, it is not just a lack of dust control that can cause paper to clog.
There are a few factors at play when you start working with a drum sander, and the species of wood has a major part in the level of satisfaction for the operator. The list below details the greasiness of certain woods and gives a recommendation for the best grit to use with your drum sander.
|Grit Size start-finish||Oil Content In Wood||Species (sample only)|
|60 – 80 – 120||Very high||Rosewoods (dalbergia spp.)|
|80 – 120||High||Cocobolo, Purpleheart|
|80 – 120 – 240||High to Medium||Butternut|
|80 – 120 – 240||Medium||Locust|
|80 – 120 – 240 – 320||Medium to Low||Poplar|
The grits above are suggested steps per grit for a particular wood that you are using. Individual logs do often contain more or less oil than average in that species so the list above is purely a guide only. It is what I have found to be the most efficient process and your experience may differ.
Aluminum Oxide Grit vs Zirconia Alumina Grit.
To dig deeper to find the best grit for drum sanders you need to consider the type of cutting material that is incorporated onto the paper or cloth backing as there are time and money cost differentials to consider as well as life of sandpaper in this section.
Aluminum oxide is the typical abrasive that most woodworkers will be familiar with and while it does a good job generally, it has limitations about cutting life.
The big selling point with some manufacturers of this sandpaper is that the abrasive grits break down as they are used and this action presents fresh cutting edges as the grit wears away. In theory this sounds alright and might even be beneficial to a random orbital sanding situation but I wonder if this wearing down activity is the best solution on a drum sander because drum sanders are primarily productivity generators meaning they exist to do a lot of work.
If the sandpaper breaks down as it wears then there is potential for the drum sander to not sand as effectively as it would with a fresh strip of paper mounted on the drum. I get that all sandpaper eventually wears out, and this type of abrasive does do the job in a small shop but the question nags at me.
Zirconia alumina is the other type of abrasive to consider.
This abrasive behaves the same way in that it breaks down over time but it is said to last a lot longer than the aluminum oxide abrasive. This is the choice for me. I would rather spend time sanding and building things than changing out sandpaper on a drum.
I recommend you do some research on the different abrasives before you set up to by several rolls of different grits to suit your machine. The other point I recommend is to keep the original sandpaper strip your machine came with as a template to cut the next one accurately once you have worn that strip out, and when ordering new rolls check the width of the roll you have already on your machine as there are several different sizes and the wrong one may not fit.
Last but not least, when choosing rolls of different grits, I have found with my machine that there is little benefit using 320 grit because the sandpaper just clogs so quickly even with a dedicated dust extraction unit connected.
The drum sander is so effective that it is impossible to keep the abrasive clear enough to cut cleanly. I stop at 240 now days and finish off with the random orbital. This works for me, and should for you. It works particularly well with end grain cutting boards.
When using an drum sander for making end grain boards I pass the boards through the sander after the first glue up when the boards are still in the side grain orientation and I just use the 80 grit alone.
There is no need to use higher grits for this step because all that is required is two clean flat surfaces and 80 grit does this really well. I use the higher grits when completing the board after second glue up and the board is in the end grain orientation.
I hope this article has gone some way to helping out with any questions you might have had. I had fun putting it together.
If you are looking at a drum sander as a shop machine, you might be interested in another article here. Are Drum Sanders Worth It.