DF500 vertical alignment problems

[kiwistate]

I’m having consistent problems with my DF500 and vertical alignment. This results in panels that have considerable ridges between boards. This has been an issue ever since I got this tool (about a year ago).

For this test, I made 4 mortises in 19.9mm thick material using the 5mm cutter. Cut depth was set at 12mm. The fence height was set to 20mm. As a result, the distance from the top reference surface to the top edge of the mortise should be 7.50mm.

When I used callipers to measure my actual results, I got 7.50mm, 7.30mm, 7.70mm, 7.46mm. That’s a variability of .4mm (or about 16 thou). Is this normal but I’m just expecting too much of the machine?

When I make panels & use the domino for alignment, I typically have to do a LOT of sanding along the joints between boards with 80 grit.

I had the workpiece clamped down, overhanging my workbench to ensure that the fence was being used as the reference, rather than my work surface. My technique is to push kinda “down and forward” on the fence handle. I then grab the tool by the power connector and slowly push directly in.

The workpiece was freshly milled & verified with a known-good square & straight edge & I was using dust collection. I've attached 4 photos showing the setup, and how I hold the tool.

My fence isn’t drifting (have verified /w callipers at the beginning and end of this trial, and only 4 mortises were drilled, hardly a marathon session!).

What else could I be doing wrong here?

 

[luvmytoolz]

This is so weird, this is the 3rd or 4th DF500 post with end result issues.

I see the board you're cutting into is overhanging quite a lot, far more than is needed to give the DF500 enough clearance, is it possible as the entire weight is being applied to the overhanging edge that you're getting a minute amount of flex/movement?

Before doing anything else, I'd suggest doing the same again, but only overhang the board a few mm from the bench edge to give the tool clearance, and see if you get a different result.

 

[Crazyraceguy]

You are not expecting too much. On a piece as small as you pictured, they should be perfect. Where people run into issues is with long parts and too much space between Dominos, especially of on board is not so straight.
I don't see a pic that shows your problem though?
As far as what is wrong. It's most likely a technique problem. Overly aggressive plunging can cause some movement in the entire unit. It is even more common when going into end grain. Slow, careful consistent pressure is your friend. I see a lot of people lift the tail slightly, as they plunge. Try holding the machine closer to the switch, not clear back on the plug.

 

[kiwistate]

Before doing anything else, I'd suggest doing the same again, but only overhang the board a few mm from the bench edge to give the tool clearance, and see if you get a different result.

Ah in this case, the overhang was big to get clearance for the fence from the head of the clamps behind. Typically I leave half an inch or so overhanging & still see the same outcome.

 

[kiwistate]

You are not expecting too much. On a piece as small as you pictured, they should be perfect. Where people run into issues is with long parts and too much space between Dominos, especially of on board is not so straight.
I don't see a pic that shows your problem though?
As far as what is wrong. It's most likely a technique problem. Overly aggressive plunging can cause some movement in the entire unit. It is even more common when going into end grain. Slow, careful consistent pressure is your friend. I see a lot of people lift the tail slightly, as they plunge. Try holding the machine closer to the switch, not clear back on the plug.

I did take a pic of the outcome, but given that we're talking about a couple tenths of a millimeter it wasn't really apparent in the photo. It results in panel glueups where one board is noticably higher/lower than the adjacent one.

I also suspect it's technique -- it's tempting to blame the tool but it's probably a me problem... I'll do some more test cuts tomorrow (and might even record a video on my phone from the side...) to ensure I am plunging directly in and not lifting the body of the tool up -- thanks!

 

[Crazyraceguy]

I did take a pic of the outcome, but given that we're talking about a couple tenths of a millimeter it wasn't really apparent in the photo. It results in panel glueups where one board is noticably higher/lower than the adjacent one.

I also suspect it's technique -- it's tempting to blame the tool but it's probably a me problem... I'll do some more test cuts tomorrow (and might even record a video on my phone from the side...) to ensure I am plunging directly in and not lifting the body of the tool up -- thanks!

A lot of guys have experience with biscuit jointers, which are far more forgiving to plunge technique. Plus, they don't fit tight enough to hold the pieces out of alignment.

 

[smorgasbord]

When I used callipers to measure my actual results, I got 7.50mm, 7.30mm, 7.70mm, 7.46mm. That’s a variability of .4mm (or about 16 thou). Is this normal but I’m just expecting too much of the machine?

So +/- 0.2mm.
For non-clamped work, that strikes me as being reasonable. One can easily tilt or have something slip that much while cutting.

 

[ChuckS]

"... I typically have to do a LOT of sanding along the joints between boards with 80 grit."

A telltale sign that something was wrong. No sanding is required per se to bring a Domino joint flush. It's not part of the standard operating procedure.

As others suggested, hold steady, go slow and stand close to the workpiece to see if it changes the results.

 

[Mike Goetzke]

Ah in this case, the overhang was big to get clearance for the fence from the head of the clamps behind. Typically I leave half an inch or so overhanging & still see the same outcome.

For this operation I would, like others have commented, have the workpiece just overhang the bench a bit and instead of clamps I would use something like the TSO TDS work stops.

From TSO:

 

[luvmytoolz]

For this operation I would, like others have commented, have the workpiece just overhang the bench a bit and instead of clamps I would use something like the TSO TDS work stops.

From TSO:
View attachment 377401

This is the way! ;-)

 

[Mini Me]

As an experiment clamp the machine to the board so it can't be moved and then cut the mortises and measure the result. If the result is better then it is a technique problem.