Join me for a strange one...

[BeanAnimal]

I would cut to within 1/16" to 1/8" with a jigsaw.. or use the spiral upcut bit to take multiple 1/8" to 1/4" deep passes 1/16" from the finished line then use the template to finish with a single full depth pass.

 

[kcress]

Most routers will accept a screw-in collar that is just slightly larger in outer diameter than the bit. The bit fits through the insert. You then build a template slightly larger than the area you want to cut out. The collar follows the edge of the template. Also, don't try to cut the full depth in one pass, make several passes a little at a time.

Todd

Ah that's what I'm looking for. I couldn't see guiding from the router's base as that would require a gigantic pattern and the radius-ed turns would be harder. Thanks for the multipass tip.

yes... the collar is a bearing that rolls against the guide/jig.

After hours of searching I can't find any guides that are bearings, only the steel/brass collars that have to slide along the template. I can find lots of bottom bearing wood bits and I can find a few top bearing straight wood bits... :sad2:

I can't find any general purpose bearing guides though I see a lot of "bearing guides" that just appear to be replacement bearings as they show nothing more than a plain bearing.

I presume a wood bit would be a problem with acrylic?

 

[BeanAnimal]

A "wood bit" will be fine as long as you are taking small passes (as i mentioned above). Spiral fluted bits work will with many materials. Straight fluted bits (HSS or carbide) will work well but with acrylic you need to really limit the depth of cut. A freud top bearing slugh cut bit will work well...

http://www.hardwareandtools.com/Freud-50-102-1-2-Inch-Top-Bearing-Flush-Router-Bit-6114656.html

In any case, there is no reason you can't use a brass bushing type guide and your spiral (or whatever) bit, just make your patter accordingly.

 

[swearint]

After hours of searching I can't find any guides that are bearings, only the steel/brass collars that have to slide along the template. I can find lots of bottom bearing wood bits and I can find a few top bearing straight wood bits... :sad2:

That is what you want, it is not a rolling bearing, the collar just slides along the template. The roller bearings are used to cut an edge that extends over the side, such as if you were laminating a counter top and used a larger than necessary piece.

I presume a wood bit would be a problem with acrylic?

Typical wood bits tends to grab and crack on the back side of the acrylic. Forsner bits do a decent job, but tend to overheat and gum-up. It also helps to have a sacrificial piece clamped on the back side as well.

As for the template, the best approach is to make it from a single panel. It requires a bit more effort, but the nicer the template, the nicer the finished cut. Cutting a closed loop is more difficult using multiple pieces clamped in place. You tend to get poor matchup of the edges, particularly if you have to change the setup for each edge.

I would use a slightly larger collar for the rough opening, so that it cuts to within a 1/32 to 1/16 of the desired size. Then switch to a smaller collar and do one continuous full depth pass to finish it off.

Todd

 

[kcress]

Cross post -

I would cut to within 1/16" to 1/8" with a jigsaw.. or use the spiral upcut bit to take multiple 1/8" to 1/4" deep passes 1/16" from the finished line then use the template to finish with a single full depth pass.

Sounds like a good plan Bean. As soon as I figure out the guiding I'll do it.

 

[kcress]

Whoa two more crosses - :lmao:

A "wood bit" will be fine as long as you are taking small passes (as i mentioned above). Spiral fluted bits work will with many materials. Straight fluted bits (HSS or carbide) will work well but with acrylic you need to really limit the depth of cut. A freud top bearing slugh cut bit will work well...

http://www.hardwareandtools.com/Freud-50-102-1-2-Inch-Top-Bearing-Flush-Router-Bit-6114656.html

In any case, there is no reason you can't use a brass bushing type guide and your spiral (or whatever) bit, just make your patter accordingly.

Thanks for the link Bean. I'm getting the picture now.
(See follow on question below.)

That is what you want, it is not a rolling bearing, the collar just slides along the template. The roller bearings are used to cut an edge that extends over the side, such as if you were laminating a counter top and used a larger than necessary piece.


Typical wood bits tends to grab and crack on the back side of the acrylic. Forsner bits do a decent job, but tend to overheat and gum-up. It also helps to have a sacrificial piece clamped on the back side as well.

As for the template, the best approach is to make it from a single panel. It requires a bit more effort, but the nicer the template, the nicer the finished cut. Cutting a closed loop is more difficult using multiple pieces clamped in place. You tend to get poor matchup of the edges, particularly if you have to change the setup for each edge.

I would use a slightly larger collar for the rough opening, so that it cuts to within a 1/32 to 1/16 of the desired size. Then switch to a smaller collar and do one continuous full depth pass to finish it off.

Todd

All right, the sliding collar is much easier to find and will allow me to use a more classical plastic router bit.

Ohhhhhh, so the collar can provide the set-in too! This is all making more technical sense to me now.

I know Bean, you're suggesting jig sawing the initial figure. Would it be easier,(less risky), to just do the collar set-in thing and do the rough route-out with the multiple depth passes? This would mean I'd just need the one template and two collar-guides. I'm fearing a bad wiggle or a hot gummy jig saw blade episode/disaster.



Thanks Bean and Todd for your help! :thumbsup:

 

[BeanAnimal]

Yes, two guide bushings and multiple passes on the initial sizing is a better plan. However, you may have trouble finsing two bushings that allow sich a close step between sizes. You can howevever use two bits of different diameter

 

[kcress]

Here we go..

I got a hold of some template guide bushings for my Porter Cable router. A 1/2" OD and a 7/16" OD. So sticking with the same router bit I get a 1/32" difference for a full depth final pass when I switch to the smaller from the larger.

The only real pain was the projection of one of the two guides was just over 1/4" and the other was almost 1/2" which precluded using 1/4" material as a template.. So I purchased a 34" x 22" x 1/4" piece of "tempered hardboard".

I then chucked both guide collets in a lathe and cut them to 0.2" in length. This allows me to use 1/4" with some to spare.

Here's the raw material awaiting routing.

Here we are mid route.

Coming down home stretch.

Done.

 

[BeanAnimal]

Thats not a lot of wiggle room to hand hold a guide on a template! You are going to have to be super careful.

Why didn't you just cut a thicker template?

 

[kcress]

Thats not a lot of wiggle room to hand hold a guide on a template! You are going to have to be super careful.

Why didn't you just cut a thicker template?

I don't wiggle..

I don't understand why all collets aren't 1/4"??

I was also worried that the tool length lost in the collet would bring me up short of what I needed. Turned out to be no problem though.

 

[kcress]

Here's the template clamped into place to guide my hand routing. Clamps in the front and a piece of blue masking tape across the back. The template is made to be flush fit across the tank's back edge so I can align it by feel.

I procured a 1/4" solid carbide up-cut bit. $28!! I also got a two blade 1/4" straight cut bit. Both have 1" of cutting length. This will get me thru the guide collet and the acrylic with room to spare.

As suggested by Bean, swearint, and hebygb, I took multiple passes on the orginal cuts. This allows the chips to get away and not clog up in the giude bushing and allows me to move the router quickly. Moving a router quickly allows cool acrylic to continually approach the bit. This is really important because any slow down means a melted mess will occur.

I took about 6 passes. This in after a few.

Here, the piece is cut completely away. The one thing I should've done better was to stop half way on the last cut-thru. Then, taped the piece up where I'd already cut, then proceed to finish the cut-thru. Because I didn't the last little bit broke away from the weight instead of being cut. Turned out to be small enough that the finish pass got it all. After the many cut passes the result was vastly nicer than the factory cuts. I could have just stopped as there was no feel-able roughness from blade marks and no horizontal depth pass lines.

But I had the collet guide and The Plan so I proceeded with the last 1/32" full cut. Wow I am impressed. The blue you see is from the masking tape over the back edge of the tank 5" away. Look and you can see the tape wrinkles even,thru the 5 inches of acrylic. I'm amazed.

The template removed. Dang! I should've stuffed something in the return line port.

What a mess...

Thanks hebygb, Bean, and swearint, for giving me the confidence to make this better. From the top the tank even looks better. The right opening is now 3" farther back than the left and makes more sense since the left one has the overflow opening. This forced a smaller opening to provide the necessary strength. They just matched the left side when making the right leaving the excessive rear deck span - that's now paired down three inches.

 

[der_wille_zur_macht]

Congrats!

 

[BeanAnimal]

Nice job and a steady hand

 

[MSU Fan]

Nice work - very impressive!

 

[kcress]

Thanks gents!

Now I have to get back to fixing it, now that I can get inside.(theoretically)

Our normal summer temperature around here is about 70F. Today it was 108F. So essentially I hid under a rock all day.

 

[Jensen12]

Not to butt in on your lowering method of the tank, but I work for a garage door company here in California, and I could make you something with a what we call a "jack shaft" operator, and rig a false floor and make it lower and raise with a push of a button, I think that would be neat, I think jacking and lowering that tank is going to get real old real quick. just my $0.02, something for you to think about in the near future maybe...

 

[kcress]

Thanks for the offer Jensen12.

I didn't realize that garage doors could weigh over three thousand pounds.

My system will also be push button after testing.

 

[Jensen12]

yeah, basically, we would just use a spring from a garage door, or make our own, for say a custom wood section carriage style garage door. pretty neat, I would love to see your tank to by the way, what part of cali are you in?

 

[eznet2u]

Very nice work. We also had 108*...You live next door to me? :wavehand:

 

[kcress]

what part of cali are you in?

About 70 miles down the coast from S.F.