Frustrations with Hammer A3-31 fence

[Tom Hassad]

Has anyone else here dealt with the jointer fence moving out of 90 degrees to the table? I planed and glued together two boards and then jointed and planed the assembled pieces to final dimensions only to find the boards to be thicker on one end and thinner on the other. The conclusion I reached is that as I passed the boards against the fence the fence moved out of 90 degrees. What is frustrating is the fence maintains its 90 degrees by balancing the thinnest portion of the fence on the jointer table when it should be the broad flat top that should serve as the base to the fence. It is backwards but there is no way to flip the fence over and use the flat top as bottom. I have searched and I cannot find if someone has made a better replacement fence or come up with a hack or trick to help keep the fence perpendicular to the jointer table. Any suggestions - I used a square and got it aligned but apparently too much pressure on the fence easily moves it out of alignment.

[Derek Cohen]

Tom, I have not experienced a flex or movement issue with the fence on my A3-31, which I have had for about 5 years now. I did wonder, however, if the fence did flex (since it looks like it could), what would I do? The one idea I had was to attach a subfence, perhaps melamine-covered ply, to the main fence to stiffen it up. One should be able to do this without losing any planing width - although this is not an issue for jointing edges.

The other thought I had about your result was what you actually were doing to obtain this result (if the fence was square)? The question I have is whether you are jointing one face and thicknessing/planing the other, or only one side before jointing the edge?

Have you had this machine long?

Regards from Vienna

Derek

[Rod Sheridan]

Hi, I’ve never had an issue, and I haven’t spoken to customers with that issue.

Are all the fasteners tight and are both 90 degree stops on the fence making contact with the fence brackets?

Regards, Rod

[Tom Bain]

I haven’t had any issues with the jointer fence not staying 90 degrees to the table, but as you probably know the fence can flex a bit (back and forth) given how its attached to one end of the machine. My solution to eliminate the flex was to place a mag switch featherboard (without the featherboard attached) behind the fence which prevents it from flexing and can be taken on and off easily. I think that might also help in your situation.

Here is a stock photo of the mag switch thing:


The also make a version that can attach to a vertical T-Track:

[Dan Friedrichs]

Has anyone else here dealt with the jointer fence moving out of 90 degrees to the table? I planed and glued together two boards and then jointed and planed the assembled pieces to final dimensions only to find the boards to be thicker on one end and thinner on the other.

How could the fence contribute to the board being different thickness?

Also, I'm totally confused about "...fence maintains 90 degrees by balancing the thinnest portion...". The fence is mounted to the rail at the end of the infeed - there isn't any "support" from the table, at all...

Tom, maybe I've misunderstood something about your post, but I think you're doing something fundamentally wrong or misunderstanding the basic functions of jointing and planing. Can you describe in detail each of the steps you've taken and in what order?

[Dan Friedrichs]

I haven’t had any issues with the jointer fence not staying 90 degrees to the table, but as you probably know the fence can flex a bit (back and forth) given how its attached to one end of the machine. My solution to eliminate the flex was to place a mag switch featherboard (without the featherboard attached) behind the fence which prevents it from flexing and can be taken on and off easily. I think that might also help in your situation.

Maybe I haven't had enough coffee, yet, because this whole thread is confusing me

What problem does the mag switch solve? If the fence moves back-and-forth, that means the fence is no longer coplaner with the length of the tables, but it doesn't change the 90 degree angle between the fence face and the cutterhead. So what's the issue?

[Mark Carlson]

I was also confused by the original question. It almost sounds like you're using the jointer and expecting the jointer to act like a planer and maintain parallel sides. The jointer gives you a flat surface or a flat surface thats 90 degrees to another side if using the fence.

My A3-31 fence does move a little but it stays 90 and doesn't affect the result. I originally put a mag switch behind the fence because I thought it would be an issue but over time realized it had no affect and stopped using it.

[Malcolm McLeod]

... the boards to be thicker on one end and thinner on the other. ...

I don't have the A3-31, but have a similar design J/P with fence mounted at the end. Narrow edge is down to allow jointing edges at <90 degrees. Flex of the fence has never been an issue - if set as such, it is 90 degrees to the table. The 'loose' end may flex laterally, but does not twist. Like Dan, I may certainly be missing something, but the only time I have gotten a board with different thickness was from edge-to-edge, and was due to uneven wear in the bed of an old planer. ...I pulled the previous owner's wooden auxiliary bed out and it was near perfect again.

Did you joint one face, then switch to planer mode and plane the 2nd face? Or just joint both faces? If the faces weren't co-planar to begin with, they may both be smooth and flat, but will still not be co-planar/parallel.

Is your issue in the width? Joint 1 edge, then rip to width, then light pass on jointer to take saw marks out of the ripped edge.

Or are you tapered from edge-to-edge (front-to-back, as you stand in front of the J/P) as the result of the planing operation? If so, the planer bed may need adjustment.

[Tom Hassad]

I am using box store 2 by 6’s and ripping them to approximate width and then I joint the side (the thin edge) and I use that to but up against the fence while I joint only one face. I do that with a second piece, then I glue the faces together and then repeat the same process with the board - joint only one edge and only one face then run the other rough sides through the planer. After several passes I will run the previously jointed sides through the planer. (Is this wrong?) The resulting Board looked like a parallelgram. I knew I did something wrong because I took two boards and pushed them together to check for square and the bottom sides were touching but there was a 1/8 gap at the top. I went back and checked the fence and it was not 90 degrees. I guess I am not tightening it hard enough. I am not pushing hard on the fence. It is not a flex issue (or maybe it is) but it is an issue where despite using the leverr to tighten the nut to lock it in position it slips. When I became aware this was n issue (kicking myself for not checking sooner and making a few parallelograms, I noticed that when I joined the side edge and pushed it against the fence to joint the face there was a gap at the top of the board between it and the fence. It fell out of alignment again. From the replies I guess I am not tightening enough although I feel I am applying enough torque to the lever and I am mindful the fence is not all that sturdy so just using it to register the alignment not pushing hard into the fence as I joint.

My point about the fence design is not well explained - the top of the fence has a 3/4 inch flat surface and the bottom part that rests on the table is about 1/4 inch thick. I wish it had more surface area to rest on the table to maintain the 90 degrees.

When I bring the fence close to the 90 degrees it is basically at the very end of its travel and you need to back out the screws on the end of the arm piece to get the final move to perfect 90 degrees.

I hope this explanation helps.

[Tom Hassad]

I want to add that maybe I glued two board a that were not square because when after I jointed the one face I noticed that of the two boards glued together one side was thicker than the other side so it looked like a triangle resting on a rectangle (exaggeration but generally that is how it looked) I thought that as long as the face was flat the planer would take off the high end and flatten it but I think in actuallity since both boards were not square that even though their faces were perfectly flat to each other I was essentially passing a parallelgram though the planer and expecting it to come out square — grandly I still don’t know quite what I did but this is the result - a board that is flat on all four sides but when stacked next to a flat edge the bottom touches the edge but not the top of the side.

[John Gornall]

The bottom of the fence is narrow so the fence can be tilted back to 45 degrees. The fence doesn't rest on the table and shouldn't touch the table.

The fence is supported on the bar at the infeed end and the sliding plate at the back over the blade. The bar on the infeed is to be set at a specific height. The sliding plate must have the metal and plastic washers installed in the correct order to set the fence support at the right height above the table.

My fence slides like butter and stays 90 degrees.

[Edwin Santos]

The bottom of the fence is narrow so the fence can be tilted back to 45 degrees. The fence doesn't rest on the table and shouldn't touch the table.

The fence is supported on the bar at the infeed end and the sliding plate at the back over the blade. The bar on the infeed is to be set at a specific height. The sliding plate must have the metal and plastic washers installed in the correct order to set the fence support at the right height above the table.

My fence slides like butter and stays 90 degrees.

To add to the advice above, it is important that the bar mounted to the infeed table be perfectly parallel in addition to being mounted at the correct height. If you think this might be the root of your problem, do a search on this discussion forum, and you should find a photo of a simple plywood jig someone built to hold the bar in the correct position for tightening. If that bar is not parallel, then the assembly is moving on a slope and will never hold a consistent position. Good news is that it is a simple issue to resolve.

[Dan Friedrichs]

Tom,

You are using the machine radically incorrectly. There is no reasonable way to reference the edge of a 2x6 to the jointer fence with enough consistency to flatten the wide faces of the board to be perpendicular to the edges. Your order of operations is wrong.

Correct usage:
1) Flatten one face (wide side). Don't use the fence at all. You're just making one face flat, at this point.
2) Attach fence. Make sure it's perpendicular to the table. This does not require extraordinary tightening of anything. Joint one edge while the previously-flattened face is held against the fence. You now have an edge that is flat and perpendicular to the first face.
3) Convert to planer mode. Make other face of board flat and parallel to the first face.
4) Use table saw to rip second edge parallel to first edge.

This is stock-prep 101.

If you're gluing boards face-to-face, you could also:
1) Flatten one face of one board. No fence used.
2) Flatten face of 2nd board. No fence used.
3) Glue faces together.
4) Treat the two as a single, rough, board and follow the steps, above.


I don't really understand what else you're doing, but I think you should disabuse yourself of the idea that there is something wrong with the machine. The fence is properly designed. The flex is normal and not detrimental to the operation at all. I think you've worked yourself into a logical fallacy of assuming something wrong with the machine before assessing if your use of it is correct.

[ChrisA Edwards]

Here's the jig, referred above. The block, glued to the plywood is 17mm. I made this and used it to mount the fence coplanar to the indeed table.

[Andrew Hughes]

I agree with Dan. I would also like to add one tip. With a pencil mark the side you faced flat to the square edge. A arrow or line anything to keep track of your jointed edge.

Good luck