Cheap tilting head Harbor Freight mortiser gets the job done.

[Mike Schuch]

I have seen a lot of talk about mortisers lately so I thought I would post a couple pictures of mine. A couple years ago I had 107 half inch square balusters to mount in some hard maple railing. Some of the railing was on stairs so I needed to make many of the 214 square holes at an angle. I was too cheap to spend a thousand dollars or more on a good mortiser so I picked up a Harbor freight mortiser for $140 with a 20% off coupon. It did a perfect job on all 214 of the holes. I love quality machines but some times cheap ones get the job done without breaking the bank.


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I built my own stand and table to mount the mortiser on.

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The tilt mechanism could not have been simpler. A good lock nut and the motiser head never moved.

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I was lazy so I mounted an old double acting air cylinder I had lying around and plumbed it through an old electric pneumatic solenoid valve with a foot pedal to activate it. I needed the double acting solenoid valve to slow and soften the downward motion with a bleeder valve. Worked great!

Some day I will come across a good deal on an XY table and make a nice vice to hold the work piece. Until then a simple wooden fence clamped to the table has been doing the job nicely.

I have no problems with people that want to drop $1000 or more on a quality mortiser. Good tools make life easier and are a pleasure to use which makes woodworking much more fun. But for the rest of a cheap tool might be just the ticket!

[Mike Cutler]

If it gets the job done correctly, little else matters. Who cares where you you bought it.

)

[Rich Engelhardt]

Which bits did you get?

I've been tossing around adding a mortiser to my collection.
I seldom have need or use for one, but, it's like anything else - if you have it, you'll probably use it.

[Keith Pleas]

I was lazy so I mounted an old double acting air cylinder I had lying around and plumbed it through an old electric pneumatic solenoid valve with a foot pedal to activate it. I needed the double acting solenoid valve to slow and soften the downward motion with a bleeder valve. Worked great!

Can you explain this a bit more? I see the cylinder, can kind of visualize the rest - but would love a complete description. I have a compressor, use it for lots of stuff, but have never engineered a pneumatic anything!

[Andrew Joiner]

It did a perfect job on all 214 of the holes. I love quality machines but some times cheap ones get the job done without breaking the bank.



I have no problems with people that want to drop $1000 or more on a quality mortiser. Good tools make life easier and are a pleasure to use which makes woodworking much more fun. But for the rest of a cheap tool might be just the ticket!

I totally agree Mike. Great idea with the air cylinder.

[Mike Schuch]

The air cylinder did take a bit of engineering.

<Design 1> I could have just put a valve on an incoming air line then plumbed the cylinder to the other side of the valve. With 50psi of air pressure this would have driven the mortiser head down so fast I could have cut a mortise without even turning on the motor... pile driving the chisel into the stock :-) Been there tried that.

<Design 2> To slow the down feed of the mortiser head I needed some way to slow the air escaping from the bottom part of the cylinder. The easy approach was to put a needle valve on the air tube coming from the bottom part of the cylinder. The needle valve allows air to pass at a slow adjustable rate. In this configuration the head would shoot down half way rather quickly compressing the air in the bottom half of the cylinder and start slowing the downward motion of the head. Then the air in the lower half of the cylinder would slowly drain off through the adjusted needle valve and lower the head slowly for the rest of the stroke. When the pressure in the upper half of the cylinder was released the head would shoot up rather quickly until enough vacuum formed in the lower half of the cylinder to slow the accent. As the air passed the opposite way through the needle valve to relieve the vacuum the head would slowly rise the remainder of the stroke.

The mortiser head would only raise if the spring raising the head had enough force to overcome the friction of the chisel exiting the cut... didn't work!

<Design 3> To provide a nice cushioned powered decent and a cushioned powered accent of the head a twin electronic valve was used. Each half of the twin valve had three ports. (Port A) Switched port to the cylinder. (Port B) Normally open Port. (Port C) Normally closed port.
When there was no power the the solenoid on each half of the twin valve (Port A) was plumbed to (Port B). When power was applied to the solenoid (Port A) was plumbed to (Port C). In electronic terms the twin pneumatic valve acts exactly like a DPDT (double pole double throw) switch (or more accurate a DPDT relay).

Since there are 2 halves of the pneumatic valve I will reference the ports on the first half of the twin valve as (Port A1) (Port B1) and (Port C1). Like wise I will reference the ports on the second half of the valve as (Port A2) (Port B2) and (Port C2).

(Port A1) is plumbed to the top half of the cylinder. (Port B1) is plumbed to a needle leak down valve then to atmosphere. (Port C1) is plumbed to the supply pressurized air.
(Port A2) is plumbed to the bottom half of the cylinder. (Port B2) is plumbed to the supply pressurized air. (Port C2) is plumbed to a needle leak down valve then to atmosphere.

When there is no current to energize the solenoid on the twin valve the bottom half of the cylinder is pressurized and the top half is at atmospheric pressure.
When the solenoid is energized the top half of the cylinder is pressurized and the bottom half is at atmospheric pressure.

At the moment when the solenoid is energized or de-energized half of the cylinder is quickly pressurized but the opposite half of the cylinder is SLOWLY depressurized because the leak down needle valve will only let the pressure escape slowly into the atmosphere. By adjusting the opening in the needle valves you can adjust how quickly the air escapes and hence how fast the cylinder (and miter head) moves.

By adjusting the PSI of the supply compressed air you can adjust the total force exerted by the cylinder in either direction without significantly changing the speed at which the miter head travels.

Does any of this make sense?

[Chris Padilla]

I'm not quite getting why you needed an air valve to control the mortiser's feed rate. Isn't there a handle that you pull down to control this? Was this just automating that so your arm didn't fall off?

[Mike Schuch]

P.S. So the temptation is to buy a second $140 Harbor Freight mortiser and mount the motiser head and slide at an angle underneath a table with the same pneumatic cylinder system. Then ditch the chisels and just use a stepped drill bit instead of the mortising chisels! I would mount the slide so the stepped drill bit would just pierce through the table at and angle when the mortiser was at the bottom of its stroke.

[Mike Schuch]

I'm not quite getting why you needed an air valve to control the mortiser's feed rate. Isn't there a handle that you pull down to control this? Was this just automating that so your arm didn't fall off?

After the first dozen holes with the lever my can of beer got too heavy!

It was fun engineering the pneumatic control. It is the first one I had done and I learned a lot!

I actually had all the parts in my junk bin. My father gave me a huge box of various pneumatic fittings and parts a while back. It was even more fun the the Erector set I had as a kid!

[Bill Space]

All I can think to say is...

HOW DARE YOU report on a successful experience with a HF tool!

I have had some good HF tool experiences too... so I can relate...

Some bad experiences too...so I can relate to the other side as well...

[Mike Schuch]

The best Harbor Freight tool I ever had was a 6" jointer which I had for nearly 20 years. I always wanted to replace that jointer with a bigger nicer jointer but the stupid thing would always work perfectly and I never REALLY could justify a bigger nicer jointer. I have my fathers 8" Jet jointer now and my friend LOVES my old HF 6" jointer.

I would not put the mortiser in the same class as the HF jointer but it sure does a nice job for cheap! If I cut mortises every day I would certainly want a nicer tool... but I have passed on a couple of CL used mortisers because this HF does fine for what I need. For those like me that always wanted a mortiser but could never justify spending $1K on one the HF might be worth considering.

And, YES, I have purchased many HF turds!

[Keith Pleas]

Does any of this make sense?

Some! I appreciate the detail. I wish I had that big box of fittings to play with!