Let’s explore a simple method to verify the alignment of jointer knives, which is necessary when changing or adjusting them.

The first goal is to have all of the knife edges across their full widths in a consistent relationship to the outfeed table. The top of the arc of the knife edge should be very slightly above the level of the outfeed table. Secondarily, perhaps after the edges wear down or the jointing performance needs adjustment, the overall height of the outfeed table can be tweaked.

There are several good approaches to dealing with this, some involving dial indicators and specialized accessory equipment, but I prefer a low-tech method. Though well-known, how accurate really is it?

Here is how I perform the test, starting with unplugging the machine. A block of wood, about 3/4″ thick x 1 1/4″ x 4 ½” long is carefully jointed (by hand) and marked with 1 mm gradations. As you can see, I like to label the jigs I make with a description and reminders. It is placed in a reference position on the outfeed table (photo above, at top).

Then, the cutterhead is carefully rotated by hand to allow the knife edge to “grab” the block and advance it through the portion of the edge’s arc that is above the level of the outfeed table. The block is deposited as the edge “lets go” and continues its arc below the level of the outfeed table. (Photos below.) Note that a wooden test block is better than a metal ruler, which the edge doesn’t grab well.

The beginning and end of this arc define a tiny chord of the knife flight circle. The height of this chord is the amount of projection of the knife edge at its highest point above the outfeed table. The test is repeated at three or four places across the width of each knife.

Now let’s correlate this height with the lateral travel of the test block, which is the length of that tiny chord. A mathematical formula involving the Pythagorean theorem gives the results, tabulated below, for the 72 mm cutterhead knife flight circle on the Hammer A3-31.

Knife

Projection       Chord          Chord

(inches)          (mm)          (inches)

.0005             1.9             .075

.001               2.7             .106

.002               3.8             .151

.003               4.7             .184

.004               5.4             .213

.005               6.0             .238

.006               6.6             .261

The method is very accurate! A mere .001″ of knife projection moves the block 2.7mm, which is easily distinguishable from no movement, which signifies no projection.

However, note that the relationship of the knife projection to the advancement of the test block is not linear. The first thou of height advances the block 2.7mm – about 3mm. However, a height difference from .002″ to .003″ only advances the block about one more mm (0.9mm).

Fortunately, I want the knives to be a only about one thou, two at the most, above the outfeed table so all I have to do is see that the block advances about 2-3 mm, or 4mm at the most, and do so reasonably consistently across the blade width, for all of the blades. Indeed, the Hammer manual recommends 2-3 mm of travel.

So, there it is: a low-tech, accurate method. But now, after having analyzed it a bit, I have more confidence in it and can use it more intelligently.

This final installment in the series will discuss changing blades in the Hammer A3-31 and some summary thoughts on jointer-planer combo machines. [The entire series can be viewed here.]

With some jointers and planers, changing blades is a tedious chore. Long ago, I struggled with the old spring-loaded jackscrew system on a jointer. Brutal. By contrast, changing blades on the Tersa cutterhead that was in the Inca jointer-planer was almost unbelievably easy and fast. The OEM system on the Dewalt DW735 planer was quite easy, and now with the Shelix cutterhead with carbide-tipped inserts installed, changing blades is practically a non-issue.

The system for changing and adjusting the blades on the A3-31 is very good, though not quite the slam dunk of a Tersa. Each of the three blades has holes that neatly register on bosses on the blade holder, which is secured in a slot in the cutterhead with four hex socket screws using the provided T-handle wrench. (See the photo above.) This is easy to do, though a cutterhead lock would make it easier.

If necessary, the blade holder-blade assembly can be adjusted for height with the four adjustment screws within the holder block. These can be used to make a consistent projection of the knife in relation to the outfeed bed across its full width. Further, the height of the outfeed table is adjustable to set its overall relationship to the arc of the knife edges.

The factory settings, which I assessed when the machine was new and the knives were fresh, were excellent; no changes needed! So, when I installed replacement knives, everything should stay the same, right? Well, it worked out pretty well, maybe actually well enough, but not quite to my satisfaction. Somehow, despite great care on my part, gremlins sneaked in and I had to fiddle with the height adjustment screws to get an a consistent projection across the width. (This is not a matter of a difference in the overall projection related to worn versus fresh knife edges.) The manual explains a simple assessment procedure to help get it right and I am happy with the results. Note that perfection is not necessary for this. By the way, another option is the helical insert cutterhead available for the A3-31 from Hammer.

Here’s the key: the machine performs accurately, consistently, and efficiently. I get the results I need to make high quality things from wood. This is what matters.

In summary:

1. For the reasons explained in this series, I highly recommend a 12″ jointer-planer combination machine for the small shop woodworker.

2. After 2 1/2 years experience with the Hammer A3-31, I heartily recommend it. As with any machine, there are a few shortcomings (for this fastidious woodworker), which I’ve covered, but this is an excellent machine that can be a great partner as you pursue excellent woodworking. I cannot fairly compare it to corresponding offerings from Minimax, Jet, Rojek, Grizzly, and Rikon because I haven’t used them, and I’d bet the $7,000 Felder AD-531 outshines all of these, but I can say I’m very glad I have the Hammer A3-31.

Now for a look at the parts and systems of the Hammer A3-31 that can be adjusted and tuned, with particular consideration to the ease, accuracy, and durability of the adjustments.

Jointer beds

When the machine arrived, the beds were slightly out of parallel to each other across their widths (i.e. in twist) – by .006″ over the 12″ width. Not bad, but having seen the potential in the excellent flatness of the beds, I wanted to improve their alignment.

Since the alignment of the outfeed table to the knife arc was fine from the factory, the twist was easily removed by adjusting only the two bolts (see the photo above) on the operator side of the infeed table to make the tables parallel within .001″.

Next, using a long straightedge, I determined that the infeed and outfeed beds were tipped along their lengths toward each other. The gap at the middle was 0.018″. To my mind, this is like have a concavity along the full length of a jointer plane sole and would make accurate jointing difficult at best.

Again, the correction was made by adjusting only the infeed table. This was a more complicated adjustment involving the pair of bolts on the operator side and a pair of setscrews, accessed under a removable panel, on the hinge side. Each of each pair of screws must be adjusted by a different amount. To make a long story short, I did a little trigonometry to prevent having to do it by trial and error. The result: cha-ching! The beds are parallel along their length within .001″.

Unfortunately, the Setup Guide, which covers these adjustments and is available as a pdf on the Hammer website, is out of date (copyright 2005). It references an earlier design of the machine and much of the adjustment parts have changed. Fortunately, Hammer makes knowledgeable technicians available by phone who were generous with their time in helping me understand the machine.

I called Hammer this week in anticipation of this post, and they favorably received my suggestion to update the Setup Guide. The User Manual, included in print with the machine and also available online, is more current and clearly explains assembly, basic adjustments, operation, maintenance, and so forth.

Planer bed

I tested this on a performance basis by planing an 11 3/8″-wide board, and by planing two narrow sticks simultaneously sent into the planer at the outer width of it. From the factory, the planing parallelism was within one thou. Wow! This is adjustable if ever needed.

Digital handwheel

This accessory, which I have found very helpful, was calibrated using the information in the Setup Guide. Reading it takes a bit of getting used to because the numerals indicate decimal inches while the hash mark increments are actually metric that approximates imperial. It is really not a problem though.

Fence

Setting up the fence accurately went according to directions, though it does take some care. To maintain a consistent angle, it is important when adjusting the side-to-side position of the fence in use to hold the sliding bracket down firmly on the extruded track while tightening the knob.

In summary, the A3-31 can be tuned to a high degree of accuracy. There are some finicky steps for those who want to tune it really well. Some documentation is lacking but help is available.

The most welcome feature is that the adjustments hold solidly over time and when converting back and forth from jointer to planer mode. This is invaluable.

Next: one more installment – knife changing and an overview.

Let’s take a detailed look at the Hammer A3-31.

When considering a new machine or any tool, I first assess the quality of the key parts that cannot be altered by the user but are accessible to direct evaluation. Here’s how the A3-31 stacks up in this regard.

1. Bed flatness is excellent. Against a Starrett straightedge, the jointer infeed table is within .001″ along its length and .002″-.003″ on the diagonals. The outfeed table is just a hair concave along its length, .003″-.004″, and the diagonals are off by only .002″-.005″. The planer table is within .002″ along its length and .003″ on the diagonals.

This all is excellent, well within Hammer’s spec of .006″, and is an important factor in how accurately the machine can be tuned. Furthermore, the beds are heavy and constructed with thick ribbing, as seen above.

2. The planer feed mechanism does not balk with 12″ wide boards. The steel drive rollers control the board unyieldingly, yet the indentations made by the infeed roller are shallow enough to disappear when the final pass is very light. With good technique, snipe is about as minimal as it gets.

The feed speed is 6.5 meters/minute (21.3 feet/minute), which makes the three-knife cutterhead at 6000RPM produce 70 cuts per inch, typical for jointer-planers in this class. Compared to the DeWalt 735 (with a stock cutterhead) at 96 cpi in “dimensioning” mode and a phenomenal 179 cpi at the slower “finishing” feed speed, the A3-31’s 70 cpi may seem a bit rough but in fact it seems to strike a good balance between producing an excellent surface and working at a good pace.

3. I like the Euro-style safety guard better than the spring-loaded “pork chop” style. I always use paddles for face jointing and it is easy to pass the board under the narrow guard, which is height-adjustable using the knob at the far left in the photo below.

For edge jointing the guard can be adjusted laterally to expose the minimum width of cutterhead. It would be better if the guard was hinged so half of it would hang down when it is adjusted very far toward the user side of the machine – but it’s not in that position too often so it hasn’t been a problem. The hinge feature is present on the company’s higher priced models.

4. Dust collection, as I mentioned earlier, is just wonderful, for jointing and planing. This helps a lot in my small shop.

5. The construction of the aluminum fence makes it very stiff. It is flat within .001″ in all directions and I cannot detect any twist. It is adjusted back and forth by using the knob (to the right in the photo below) and sliding the bracket on the extrusion track.

A slight complaint is that the squareness of the fence to the table cannot be made exactly consistent throughout its full adjustment range and most of its length, probably due to minute errors stacking up. However, the discrepancies are quite small, and by finding favorite locations for the fence, I have had no problem getting nice square edges on long boards.

From the back view, you can see that not much sticks out – only the rear cutterblock cover. For most fence positions, the net depth of the unit is about the same with the jointer beds down or raised.

Other key components that I cannot directly assess seem very good based on indirect observations and working with the machine. Machining and part formation looks neat throughout, with no ill-fitting components. The motor has excellent power and does not get overheated. Hand adjusted parts, such as the planer bed adjustment are very smooth, and the machine runs with that nice low hum suggestive of quality.

The same outfit that makes Hammer machines also makes the much more expensive Felder line. A Felder 12″ jointer-planer lists at over $7000 (ouch, my hand just cramped up at the keyboard), which is more than twice the price of the Hammer A3-31. I figure that the expertise and institutional experience applied to the Felder line must bleed over into the Hammer line. I’d bet it’s more than half the machine for half the price.

Next: The final next installment in the series will cover tuning and results.

Having established in the previous post a rationale for this type of machine in a small woodshop, let’s take a look at the Hammer A3-31, which I’ve been using for the past two and a half years.

Getting it into the shop

I’m afraid I must start with one of the few problems I have experienced with the A3-31: getting it into my shop. The mobility kit uses a single axle that attaches to the base parallel to the 55″ jointer bed, along with 4″ wheels that simply turn in one plane – they do not swivel. A lifting bar is inserted into a cleat near the bottom of the base of the machine to roll it in a straight line and make partial J turns.

The top photo shows the lifting bar in place. One wheel is visible at the lower right of the machine base.

The system works well in the shop but it will not get the machine through the 32″ doorways in my house or the 36″ doorway of my shop. To make matters worse, the A3-31 was shipped on a pallet built for a special narrow-fork pallet jack. I ended up having to transfer the machine from the pallet onto a dolly that I built and use plywood sheets to get it over doorway bumps – a big hassle. If you have a garage shop or other wide doorway, all of this is not a problem.

To solve this problem, I wonder if Hammer could include a short axle to attach to the base perpendicular to the jointer bed to be used with a matching cleat. It might work only with the jointer beds raised but that would be good enough to just get the machine through narrow doors. Hey, Hammer: this would help many small shop woodworkers.

Now on to happy issues.

In order of frequency, here are the most common concerns among woodworkers that I’ve heard and read about j-p combo machines:

1. Changing between jointing and planing modes.

Fuhgeddaboudit. To go from jointing to planing, the fence stays in place. You lift the jointer beds as a unit, then flip the dust hood and reattach the hose. The tables remain parallel when raised so the effective width of the machine is approximately unchanged. The planer bed is cranked into position with an extremely smooth and fast mechanism. The jointer beds return to position precisely. Really, it’s all fast and easy.

Here are the beds lifted:

And here the dust hood is in place for planing with the hose attached:

This is the planer infeed with the bed raised into place. The adjustment mechanism has the helpful, optional “digital handwheel.”

2. Jointer bed length

Is a 55″ jointer bed long enough? It sure is for anything I do. I have no problem routinely accurately jointing rough boards 6′ long. In my opinion, there is no need to have the entire board length supported on either the infeed or outfeed table to do accurate jointing.

If you want more length, Hammer offers optional extensions for jointing and planing that look like they attach very easily.

3. Dust collection

Can the dust hood contraption really work in both jointer and planer modes? Yes! The A3-31 is nearly perfect when used with my Oneida Mini Gorilla cyclone collector. It is the tidiest machine I’ve ever used.

4. Accuracy

Can a combination machine be as accurate as single function machines? This was my number one concern when contemplating the purchase.

For a given quality level, having used the Inca for many years, and now the Hammer, I say the answer is yes. I did have to do considerable work tuning the A3-31 to my liking but I’m a rather fastidious worker. (“Really, Rob? You? Get outta here, I wouldn’t have imagined . . .”) The key is that this machine can be tuned and it holds the settings. More on this in a future post.

5. Power and mass

Are these machines, in this size range, just toys for dilettantes? OK, now I’m getting a little annoyed. Just fuhgeddaboudit, OK? The motor is listed at 14 amps/220V and does not balk at planing full width boards. The mass of the beds, the quiet operation, and the results it produces are real deal.

[This extended review of the A3-31 and the general topic of j-p combo machines are unsolicited and uncompensated.]

Next: getting inside the machine.

In the previous post in this series, I recounted my stock preparation history culminating with the Hammer A3-31. Prior to discussing the ins and outs of the Hammer machine, let’s look at the rationale for a combination jointer-planer in the small shop.

I’m guessing most of us share the following woodworking profile. We have:

• A strong desire to build things from wood that exceeds the desire to dawdle with woodworking tools.
• Less time than we want for making things.
• Less shop space than we’d like.
• Less money than we want.

To get a pile of wood transformed into a finished project, the stuff needs to be taken to the desired thicknesses, with flat parallel surfaces and a straight, square edge before being ripped to width and crosscut.

Here are some options:

1. Handwork/hybrid

Doing it all by hand is just too slow and tedious for most of us, but a hybrid approach employing a portable thickness planer is very practical. One face is made flat but very rough using scrub and jack planes, just enough so it does not rock or distort on the planer bed, and there is no bow (lengthwise curve on the face). The planer flattens the opposite face, the board is then flipped and the planer makes the first face flat and parallel. Then hand plane a straight edge.

Don’t forget too that a well-tuned bandsaw with adequate blade height can do a pretty good job as a jointer and thicknesser followed by clean up with hand planes.

2. Exceptions

It does pay to be able to fully prepare a board entirely by hand just as a baseball player must be able to bunt – it isn’t used often but a complete player artfully brings up the skill when needed.

Some boards are too short to safely feed to a thickness planer and hand work is a must.

Also, there is an occasional board in which I want to preserve every hair’s breadth of thickness, and conservatively flattening one face by hand is a less risky method.

For very wide slabs, elaborate router jigs can be set up but finding a local commercial shop with a megabeast thickness sander makes more sense to me.

3. Separate jointer and planer machines

The big problem here is that jointers with widths that approach even inexpensive portable thickness planers are big and expensive. To me, it makes little sense in terms of expense, space, and work efficiency for most small shop furniture makers to have a $2000, 600-pound, 8″ jointer with a 7 foot bed paired with a 13″ thickness planer. Or how about 5 or 6 thou for a 900 pound 12″ jointer?

One interesting exception to this mismatch situation is Grizzly’s G0706 12″ jointer that has a 60″ bed.

4. Combination jointer-planer

In a single machine with a fairly small footprint, you get an excellent 12″ of planing and matching jointing capacity. This opens up a world of managing wide boards with ease. This is value.

There is a range of prices starting at about $1800 up to twice that, among options that include Rikon, Grizzly, Jet, Rojek, Minimax and Hammer. Pair one of these bad boys with a steel frame bandsaw with a matching 12″ capacity and life is very good.

Lower budget 10″ models are available, including Rikon, Jet, and Grizzly. I will say that I really appreciate the extra two inches and extra beefiness of my current Hammer over the 10″ Inca I had. Hey, how about 16″? Sure, if you’ve got the space and money, but for most of us it’s not necessary for most furniture making.

In the next post in this series, I’ll go into some detail about my Hammer A3-31. Previewing, here are two non-issues: bed length and change over between functions.

Stock preparation is the essential foundation for any woodworking project, and there are three keys to doing it well: accuracy, efficiency, and knowledge. A jointer-planer combo machine can be a big help.

There are countless pitfalls in stock preparation that can haunt even the most skillful woodworking that may follow. Twist, convex edges, and bowed surfaces are common inaccuracies that create problems. As for efficiency, well, I like making things and I do not want to spend forever grunting out stock, so the noise emanating from well-tuned machinery is music to my ears at the start of a project. Still, none of this works if a woodworker fails to appreciate wood movement from moisture exchange as well as from stresses created in the drying process.

By way of explaining how I settled on the combination machine, let me recount my stock preparation history. I think many readers will relate to much of it. Very early on, two things became obvious. First, it is very limiting to use only the thicknesses available in pre-dimensioned hardwoods, and second, dimensioning with only hand tools is slow and really not a lot of fun.

So, I got one of those ubiquitous cast iron 6″ jointers, and rigged up a marginally effective way to also use it as a thicknesser. Then, some years later, in the late 1980s, I bought a Ryobi AP-10 portable thickness planer, and its 10″ capacity made me feel like I was in heaven (“. . . man”). Still, I was stuck with only 6″ of machine jointing capacity and, despite trying the workarounds found in the tips sections of magazines, I was still doing too much hand work and longed for more machine jointing width, especially since I enjoy using fairly wide boards in my projects.

Enter, the Inca 10″ over-under jointer-planer. This wonderfully accurate machine, with its precise cast aluminum tables and great Tersa cutterhead, served well in my shop for more than ten years, perched on the feature-rich, battleship-grade stand I made for it. The only thing the dear Inca lacked was a lot of muscle, and so when I upgraded, I felt at peace selling it to a musical instrument maker.

Now, after 2 1/2 years of using the Hammer A3-31, and privately answering many inquiries about it, I’m ready to write. The opening photo shows off its width. I will discuss the A3-31 in some detail (spoiler alert) – I like it! – but will precede that with a post to consider the merits of the whole idea of a jointer-planer combo.

One more thing. I made the case several years ago for a portable jointer-planer as an excellent choice for a first machine for small-shop woodworkers making furniture and accessories. After many discussions with woodworkers during the ensuing years, I still hold that opinion, though I certainly understand how many feel a bandsaw should be first in line (I place it second) among other valid opinions.

Keep in mind that with a thickness planer as the only machine available, the initial jointing of one face by hand (which, again, I’d rather not do!) only has to produce a surface that will sit on the planer bed without twist, bow, or flex. It can be ugly with tearout, scrub plane gutters, or whatever; it just has to register on the bed so the planer can produce a flat surface on the opposite face. Then the board is flipped over, etc.

Just a few woodworking machines have the adaptability and almost the friendliness of hand tools. Chief among them is the bandsaw, but the compact router, especially the DeWalt DWP611, also earns a place in that category.

In the stage of building where the big machines have been unplugged, the radio is on, and the hand tool work is proceeding, it still is handy to call on a controllable, precisely adjusted tool that has more power than a horse.

For example, in mortising for hardware, I will clear the bulk of the waste and produce an accurate final depth with freehand routing. Rather than set up a jig or fence for the router, I simply chisel to the side layout lines, though this has been made much easier by the router.

On the other hand, for the socket part of a short sliding dovetail, I make a dedicated jig and use a bushing. The only chisel work is to square the end.

My general approach is to use the power of the compact router and, when convenient, its precision, especially in depth. I take advantage of its maneuverability for freehand work and use jigs and fences when necessary or when there is a clear advantage in overall time spent.

The best feature of the DWP611 is the precision cutting depth adjustment. The indicator on the large black adjustment ring moves more than 1/4″ along the adjacent yellow scale ring for each 1/64″ of depth change. When adjusted in the upright position, backlash is minimal but even that amount can be easily cancelled by resetting the zero mark on the scale ring, which is movable. After the depth is dialed in, the cam clamp holds it reliably. In this way, cutting depth adjustments rival the precision of a paring chisel or router plane.

This is a larger and heavier tool than the Bosch Colt and the Ridgid model but I found neither could be adjusted in cutting depth with the precision of the DeWalt, which is still easy to maneuver with one hand. I’ve used the DWP611 for about three years now and it is my clear favorite.

The 1/4″ collet is a two-piece self-releasing type, a must for any router. Unfortunately, bit changing involves one wrench and a shaft lock, a sadistic system, though I suppose DeWalt can be forgiven considering the tight quarters of a tool this size. The clear plastic sub-base has an extension on one side that improves stability for edge routing. The base can be repositioned for an optimal configuration of hand grip and sight line. I also bought the accessory base for standard bushing inserts.

The two LED lights that straddle the collet are invaluable for freehand work. The soft-start, 7 amp motor gives surprising power for a small tool.

This tool feels so friendly in hand that it might cause you to let your power-tool guard down. When routing, I remind myself that this little guy really does have more kick than a horse. Also, there is a tendency with this type of tool to get in close to the spinning bit and flying chips, so safety goggles are a minimum must.

A set of 1/4″-shank carbide straight bits down to 1/8″ cutting diameter is helpful for freehand work. Use good judgment and very conservative depths of cut for narrow bits. I also have a 1/16″ bit but I avoid using it.

So, hand tools and power tools can play together. I like to use the advantages of each to find simple and reliable ways to get the work done.