This guide contains suggestions and details on using floor sanding machinery to sand a solid timber floor. It is a guide for DIY users. If you are planning to sand your own timber floor you can achieve a good result with a little extra information.
This is about as simple a guide as you will read. It is designed to give you a good overview and step by step instructions. You can skip to the concluding step by step table and refer back to key chapters if you want to go straight into the sanding process. If you are unclear on anything you should seek local professional assistance to be sure of what you are doing before you proceed.
No warranties are given or implied in this publication. All information is provided in good faith and is accurate at the time of publication. The author asserts that it is reasonable for the reader to seek out professional assistance should any part of the subject remain unclear or if any aspect of the process is too difficult for the reader to undertake.
No part of this work should be copied without the authors’ written approval. All pictures used in this work were taken by the author.
The author runs a successful timber flooring company, has several decades of experience in flooring & teaches DIY seminars monthly.
INTRODUCTION
Any person who hires machinery to sand their own timber floor is taking on a reasonably complex task. This guide is designed to make the job relatively straightforward. Over five decades, the process of sanding and finishing a timber floor has been refined considerably. This simple guide draws on over 30 years’ experience to try to make the process as simple and as easy as possible.
I have personally assisted many thousands of people to learn how to sand a timber floor on a DIY basis. Recently I discovered eBooks and decided that I would put together this simple pictorial guide. The guide contains many pictures to try to make the whole process as simple as possible. It was decided to make this guide available for less than two dollars. We figure that anyone willing to put the work into preparing their own timber floor would see the commonsense in spending a couple of dollars on getting a little bit of real tuition. If that is you then we look forward to hearing how you go.
I have seen many thousands of timber floors completed successfully by DIY sanders who understand the process. I have conversely seen thousands of floors full of divots and marks that did not look particularly good. These floors belonged to those who have tried to use the powerful floor sanding machinery without really understanding the process.
Sanding is a relatively simple process once you understand it. However it is not something that you can simply pick up. For example, with most trades there are tips and tricks. In sanding a timber floor there are overlaps points you need to understand that relate to each of the three machines. You need to know this. Otherwise you would never know when you are ready to move on to the next machine. It is this lack of tuition and lack of understanding that has resulted in so many damaged floors over the years.
Don’t damage your floor. Stop and accept a little tuition.
Sanding equipment and tools
In this section discussing sanding and finishing we discuss how to sand solid timber floors. Solid timber floors are those that through the cross-section are completely made of a single timber.
The evolution of the sanding process has gradually developed over a period of many decades. In the modern era we use a standard set of tools and equipment and the aim is to achieve a very high grade of finish to the timber floor. Since the early 1990s developments in sanding equipment, abrasives and methodology have allowed for major improvements in the way that floors are finished. The range of tools that are now used has broadened substantially to include a number of small tools. Abrasive quality and consistency has also played a key role in improving the standard to which the timber floor may be finished.
Belt sander in use
The core machinery used in sanding has three central pieces of equipment.
The drum sander or belt sander
The main workhorse in the timber flooring industry has been the drum sander. This machine is required for the major leveling work in addition to coarse and medium sanding. In recent years the drum sander has been challenged by the arrival of belt sanders. Although these machines were initially regarded with skepticism they are now seen as offering a major improvement as for a sanding activity is concerned.
Standard Belt Sander
The drum sander is more versatile in that it can be used to sand concrete; something that you should never use a belt sander for. At the same time a belt sander offers a way to achieve a higher standard of finish to the timber surface more quickly than would normally be the case using a drum sander.
Both machines appear similar upon first inspection. Basic to both is a chassis on wheels that carries a large electric motor. This motor is used to drive the drum or belt as well as a vacuum system. Power from the motor is transferred to the drum/belt and vacuum system using drive belts along one side of the machine. On professional machines the additional feature that the machines both have in common is a clutch system that allows the machine to raise and lower the sanding abrasive. Where the machines differ is on how the abrasive is fitted to the machine.
Drum sander
With this machine the sanding abrasive is in sheet form. The drum itself is a rubberized unit that has a split for tensioning the paper. The precut abrasive sheet is wrapped around the drum and the two ends are slotted into the split where tension rollers grab the paper on adjustment. Alternatively the two ends of the paper are held in place using a metal plate.
Belt sander
With this machine the sanding abrasive is a belt. It is vital that the belts used on a belt sander have a good join in them. Companies specialize in producing belts with joins of different types designed to have minimal impact in the sanding process. The drum is a rubberized unit that sits below a top roller. The pre-sized abrasive belt slots over the top roller and the drum. In this way that is no split or metal plate to strike the floor.
The abrasive is said to be a continuous belt and this is how the belt sander achieves a smoother sanding action that appears to sand the floor to a higher standard more quickly than would be achieved using a drum sander. Because the belt floats freely between the rubberized drum and the top roller it is essential that everything is sized accurately. Top roller technology is extremely accurate.
Side View Of Belt Sander With Top And Bottom Rollers
The edge sander
It is vital that the perimeter of the rooms are sanded for a good finish. This is where the edge sander is important. These units are purpose made to achieve a good leveled finish when sanding along the perimeter of the room. Usually the edger consists of a motor that drives a 7 inch or 178 mm diameter disc. This disc is driven at high speed; above 2500 rpm. When you first pick up an edger you might be tempted to believe that the machine is designed to cut the floor on the whole 7 inch disk whereas in reality when looking down from above the edger the machine is designed to cut at just the top right hand section of its sanding action; on a clock face this would be between 12 o’clock and three o’clock.
A selection of Edge Sanders
A huge amount of power is transferred to just a small area of sanding disc to ensure that the floor is level. The machines are awesomely powerful and can do a lot of damage if not controlled correctly. You do need to be shown how to use one of these machines.
Abrasives are usually fitted to an edger using a central fixing plate. This is slightly countersunk so that it does not come into contact with the floor. The 7 inch disks are supplied with a central hole and are easily fixed into place.
A rotary sander is a vital part of the sanding process. These machines are basically polishers that are usually equipped with stronger motors and gearing.
When sanding timber it is usually considered good to use a slower rotary sander with a revolution below 300rpm.
The rotary sander should be viewed as a finishing machine that smooth’s the timber surface prior to applying the coatings. It should not be used for long periods. It is the fine sander.
Rotary Sander In Use
One of the real problems using the rotary sander is the potential to leave marks behind in the floor. The rotary action can leave semicircular marks that look distracting to say the least. [This is less of a problem with slow speed rotary sanders, which are preferred.] If these marks are left in the timber and coating is applied the resultant dark marks are there to stay unless the finish is removed.
It is important therefore to take every step when using the rotary sander to ensure that none of these marks are left behind.
Typical Floor Site
The rotary sander then is not simply sanding the floor to remove marks. The rotary sander is used to condition the timber and bring it to an even fiber level so that when the finish is applied there are no shade differences in the floor or the finish. The rotary sanding process is both a fine sanding stage and a floor conditioning stage.
General Comments
The sanding process must be viewed as a whole. When using the initial sanding machines belt or drum and edge sanders it is necessary to leave the least number of marks in the floor possible. To this end start with the finest grit that you possibly can so you do not put deep scratches into the floor. Often it is while using the rotary sander to try to remove these deep marks that the rotary sander introduces its own semicircular pattern with the resultant problems described already. Start the sanding process using the finest sanding grit that you can and you remove this problem to some degree.
Additional Tools
In addition to these principal tools there are a number of small hand tools that different contractors like to carry. These include little corner sanders, flat semi orbital sanders and small rotary sanders. From time to time there are sections of the job that required the odd extra tool. A professional floor sander will usually find that while he has these three main tools he carries five or six small power tools in addition. From the DIY perspective usually the home handyman has one or more tools that will get into places these other machines cannot reach. If you do not have a power tool it is a matter of working by hand. Often times in corners I have found this to be a better technique e.g. sometimes after scraping a corner it is easier to sand by hand.
The sanding process and dust control.
Occasionally you may see vans driving around advertising dust free floor sanding. At the time of writing all machines generate dust no matter how advanced the unit is. Certainly we have come a long way in the styles of machines available and they do collect a lot of dust in the sanding process. Drum sanders, belt sanders, edgers and rotary sanders can all be equipped with effective vacuum systems.
Machines Use Bags – When these are one third full it is time to empty them
Usually only the rotary sander is supplied with an optional vacuum; with all of the other machines vacuum systems are built in. The idea behind the vacuum system is to minimize the exposure to sanding dust for the operator. Obviously if the room was full of sawdust it would be impossible to sand the floor effectively as it would be hidden from view.
The same motor that drives the sanding system also drives a high speed fan in most of the machines. This high speed fan allows for the removal of over 95% of the dust. In fact if you have used an older style machine or a nonprofessional sanding machine you may be surprised at how little dust is generated by a modern belt sander. A modern belt sander has such an efficient design for the pickup of dust or there is actually very little left behind.
However all sanding systems that remove significant quantities of stock [or timber] from the floor will require a very efficient take-up of dust. In the case of sanding machines the sawdust is transferred into a large bag. On the drum sander this is plainly in view above or to the side of the machine and with the edger this sits behind the sanding column. This bag is designed to take a lot of dust and in order to work effectively the bag fabric must allow some very fine dust to pass through. The rule is: when the bag is one third full then it is full. Empty it.
A small amount of very fine dust will settle in the home. This is basically unavoidable. Knowing that it will happen it is possible to take steps to minimize the impact that this fine dust may have on fixtures and fittings. For example it is usually good to seal off rooms that will not be part of the sanding process. This will limit the intrusion of the fine dust. Also with curtains and similar fabrics these can be either removed or covered in plastic. With intricate light fittings it is important that these be covered as often dust will settle.
Sanding the floor
The Sanding Process Step-By-Step
This discussion is designed to be an all inclusive look at the sanding process. There are many different types of timber and many different sites that may be considered. In this discussion we cover new timber floors as well as old timber floors.
The Three Areas of Sanding Activity
Sanding grits used in flooring range from 16 – 380 grit though the two extremes are not usually necessary. The lower the figure the coarser the grit. Grits are based on a 1 inch mesh and the amount of grit that will pass through it. For 16 grit there are 16 mesh openings per inch and so forth.
With abrasives the standard of hardness is measured in Mohs with talc being 1 and Diamond 10.
Sanding
The first stage.
When you have an area to sand the first stage of the job to fully inspect the site to ensure that it is ready for the sanding work to proceed. With a new floor this is simply a matter of ensuring that all of the nails are punched down well below the surface and that nothing is loose. If you have just installed a floor you would need to make sure that you have allowed sufficient time for the adhesive to dry properly. In the case of a new floor it is relatively straightforward however it is different with an older floor. This floor needs to be checked to ensure that it can be sanded. If there are existing floor coverings on the surface these would need to be removed so that you can inspect the floor correctly; it is not sufficient simply to lift the corner of an existing floor covering and say, “yes it looks okay.” With older homes there are often repairs that are concealed from view and that can only be seen once the floor covering is removed.
Check the Floor
Walk over the area of the floor and ensure that everything is sound. With very old floors that may be installed over joists you want to test that the floor does not have any undue spring in it. Sometimes things settle and there may be dips in the floor. If you attempted to sand the floor at this stage the machine would follow the dip and wouldn’t sand correctly. If any remedial work needs to be done this must be done prior to any sanding activity.
Sanding and finishing over a problem means that it will be considerably more expensive to fix the problem later.
Punch All The Nails
So the first stage of any job is always to inspect the floor to ensure that it is ready for the sanding work. All nails must be punched well below the surface and everything must be solid. When it comes to the punching stage you should consider obtaining a punch that will not enlarge the nail hole dramatically. Some punches are quite stubby in appearance whereas others are long and slim. The idea is to punch the nails down without unnecessarily enlarging the hole.
Note; sometimes old floor coverings contain asbestos. You must not sand material that contains any harmful substance. If you even think that there could be a harmful material present or you are not sure, you should obtain professional advice. This is not simply to follow rules; it is a serious health issue.
Stage two
You’ll need to clear the area of all furniture and anything that could be damaged in the sanding process. Fabric can often become laden with dust. Sometimes it is difficult to remove drapes or curtains. These might be covered with plastic as long as there is some way of sealing them away. Dust is a consideration as it can get into all sorts of difficult places. The dust given off by sanding machines is extremely fine. Thus it is best to remove anything that could be damaged. It is also important to clear any foodstuffs out of pantries or other areas if you’re going to coat. This can become contaminated with the gassing as the coating dries. Do not attempt to work around these problems as it simply creates work later.
Bearing in mind that dust can travel for considerable distances it is a good idea to seal off areas that will not be included in the sanding process. Use a reasonably heavy grade of plastic as there is a chance that it will be caught at some point. Tape off where necessary with easy release tape. Obviously there is a limit to what you can do in this area but take every reasonable precaution. It will save you some cleanup time later on in the job.
Stage three
By now the site is clear and the floor has been inspected. You are ready to obtain the sanding machines.
Obtaining good-quality sanding machines for hire is an extremely important aspect of the task in hand. If you talk to people who have sanded their own floors a great number will say that they wish that they had never done it. This often relates to the style of machine that was used as opposed to any major fault on their part.
Some of the sanding machines available are very lightweight and are not necessarily suited to the professional sanding process. As you have seen earlier in this section there are three principal machines that should be used. What do you look for in the hire machine?
1 Firstly I would always choose a belt sander for any sanding activity. The endless belt is a much better design of machine for finishing timber. These are considerably more expensive machine to manufacture; you can often purchase three lightweight hire machines for the cost of one endless belt sander. You may find that you pay a little more to use the right machine. However in the final analysis if you leave all sorts of marks and dips in the floor as a result of choosing to use a cheaper machine, you’ll really wish that you’d spent the extra 20%.
Endless Belt
- One of the advantages of a professional belt sander is that it has a clutch present at the top next to the handle. Why is a clutch important? With some machines that do not have clutches this is the procedure. You turn on the machine which achieves a speed of around 600 to 800 rpm and then you lift the handle and thus tilt the machine so that the drum comes into contact with the floor. You then proceed to walk across the floor trying to somehow maintain an even pressure on the drum. It is pretty easy to see that what happens is that there is a moment’s hesitation as you drop the drum onto the floor. This produces an indentation in the timber where you started. Also because you are using a lifting action and trying to maintain an even pressure as you walk across the floor [virtually impossible] you end up with an uneven result. And the fact is that the only way to fix that result is using a professional sanding machine if there is sufficient timber left. I think this nicely illustrates why we prefer machines with the clutch.
When you have a machine with a clutch you start the machine and it achieves its speed. You then begin to walk forward and as you do so you use the clutch to gently lower the drum onto the floor. I call this process “feathering in” and it is a gentle way of bringing the abrasive into contact with the timber.
Once the clutch is down it arrives at a preset pressure that is maintained by the
machine [not by you] as you sand the floor.
As you approach the far wall you gently use the clutch to lift the drum. As you begin to walk backwards with the machine in motion you gently lower the drum once again. Thus you can be said to be “feathering in” & “feathering out” as you sand the floor. This is one of the only ways you can use to avoid getting those dips and divots in the floor.
Clutch
The clutch is therefore the key to the way that the sanding machine is operated. If you hire a machine that does not have a clutch then a lot of things are left to chance and trial and error. When you use a sanding machine that has a clutch you should ask the hirer to demonstrate the system to you so you can get the feel of the machine. It is a relatively simple system and you should have no difficulty in mastering it if you have reasonable hand eye coordination.
- Take a very good look at the edge sander. Edge Sanders are designed to cut in a specific position. If you are looking at the face of a clock they would cut between 12 o’clock and three o’clock. So when looking down from above the sander you can imagine the clock face and see where it should sand. Examine the machine to see whether it has been setup to cut a little to the front right. If it has this is good. [The cutting angle for the edger is usually 3-4degrees.]
- You’re now looking for a rotary sander. Because these machines do a lot of work usually when you hire them they do tend to look a little tired. Do not be put off by appearances as often some of the older looking machines work extremely well. However you still want a machine that works properly. Usually a rotary sander is a machine that has a 16 inch or 400 mm base on it. The pad on the base of the machine would normally need to be in good condition. Oftentimes this is simply a white superfine buffing pad and these do work extremely well. You can also obtain a micro finishing pad that will hold abrasive very firmly in position. You might ask if such a pad is available for fitting to the machine. Not that it’s an absolute must but it is nice.
You will want to try the rotary sander before you leave the store. There is an art to using them. It is important to know where to position the handle. Usually this is a little way below the waist, however each machine has its own vaguery and this can easily be demonstrated.
When you start a rotary sander for the first time it will often give a reasonable kick to the left. Until you have mastered the way to drive the machine it is usually best to try running it with just the pad on the base rather than any abrasive. Rotary sanders are moved by raising and lowering the handle. When you raise the handle the machine will naturally want to swing to the right whereas when you lower the handle it will naturally want to move to the left. If you lean towards the machine you can work it nicely away from yourself and vice versa you can pull it toward yourself. You’ll find that there is a neutral position and once you know where it is it becomes a very easy machine to operate. However the first time you try it, it might surprise you.
Equipped With A Vacuum
The rotary sander should be equipped with a vacuum. Check that the vacuum works and that the skirt around the machine is complete. The vacuum system is based on a small vacuum motor that draws dust from the area covered by the skirt at the base of the machine.
- Your abrasive selection is also extremely important when you go to the hire shop. The fact is that you usually cannot buy the abrasives anywhere else. So you have to get the right grit range for the job. You would want to know the name of the timber that you are sanding and already have had a good look to see how much leveling work is required. When you rub your hand over the boards you will discover if there is a height variation that will need to be smoothed out. Advise the people at the hire shop of what this deviation is and they can usually tell you the right abrasive choice.
Sanding Belts
Be extremely concerned if you are recommended to use an abrasive that falls below 36 grit. With modern-day abrasives the very coarse grades are very aggressive. Dropping down to a 24 grit belt for example will probably extend the job considerably as you will have to spend time getting those scratches out of the floor. We will often attempt to start a job on 40 grit or even 60 grit if the floor is quite even.
You also want to know what finish you are using on the floor as this will determine how fine you need to sand with the rotary sander.
As a general guide for solvent based coatings you can finish the floor at between 100 grit and 120 grit.
With waterborne coatings as a general guide it is nice to finish it around about 220 grit.
With oil usually you need to go to the same level as waterborne.
With high grade Polyx oil/wax coatings usually 80-100grit is plenty.
When you leave the hire shop you should have sufficient abrasive for the belt sander, edge sander and rotary sander to take the job from start to finish.
As a rule of thumb you should have 40grit, 60grit & 80grit belts plus 40grit & 80grit edger discs. You should also have 80grit, 100grit & possibly 120grit discs for the rotary sander.
| Standard Set | Number of |
| 40 grit belts | 5 |
| 60 grit belts | 5 |
| 80 grit belts | 5 |
| 40 grit edger discs | 5 |
| 80 grit edger discs | 5 |
| 80 grit rotary discs | 2 |
| 100 grit rotary discs | 2 |
| 120 grit rotary discs | 2 |
- As you’ll see in the sanding discussion one of the most important stages of the job is vacuuming regularly. A clean site is the key to a good job. You may need to hire a good-quality industrial vacuum cleaner. One of the problems with vacuum systems is that many of them will draw dust into the machine and then dump some of it back out onto the floor through the filter system. There are different qualities of vacuum cleaner out there and you should attempt to hire the best machine that you can. This is governed more by the filtration on the machine than by the size of the drum. Don’t be impressed by size but rather on how good the filter system is.
As you’ll note both the drum sander and edger have bags fitted and do have good sanding vacuum systems however you should not think that this means that you will have a dust free site. You will need a good vacuum and many household vacuum systems can be killed off trying to cope with the fine dust left behind from timber.
Note on Bags
When looking at hire machines you should also ensure that the dust bags that are supplied with the machine are in good condition. This does not mean to say that they have to be new. Dust bags look quite old after the first or second job. However they should not have rips in them and when the cord is secured to the machine it should seal relatively easily. With edger bags they tend to wear on one side. So just make sure that there are no holes.
Safety. READ ALL SAFETY GUIDELINES SUPPLIED
There are several elements of the sanding work that raise safety considerations. The guidelines supplied with power tools are very specific and should always be checked prior to using tools. Important areas include hearing, sight, respiratory and joints. Safety cannot be minimized. When using power tools ensure that all instructions are followed carefully.
Sanding machines are powerful and in the sanding process generate a lot of noise. Therefore it is important to wear a good-quality pair of ear muffs. These come in different grades and quality. However you will find some very well priced ear muffs that provide around 29 dB or 30 dB of hearing protection & this is about the level that you want to work with. If you find this uncomfortable it is possible to use a pair of earplugs inside the ear muffs as long as you still have sufficient hearing for safety.
Safety glasses are also needed. In the course of working with an edger it is easily possible to catch something that flips into the eye. In the course of floor sanding it is very good policy to wear eye protection. Good safety glasses fit nicely to the face and are not easily pierced by flying objects.
When it comes to the respiratory system there are many aspects of the job where you need to protect yourself. Timber dust is very harmful. Therefore it is important to wear a mask during the sanding process. Also when it comes to the coating job while it might seem uncomfortable to wear a respirator, should you choose to use solvent based coatings it would be unwise not to do so. You should always wear the appropriate protection to protect your respiratory system from harm. The better quality that you use; the better for you. As always be aware of safety guidelines from the manufacturer.
Knee Pads
Working in timber flooring is especially difficult on the knees. A good-quality pair of soft knee pads is a must. Choose comfort and your knees will thank you.
Sanding machines do draw a significant level of power from the grid. Therefore it is important to have a safety cut off box. Oftentimes the hire shops will supply this box. It contains switches that will turn the power off should there be a short.
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