Cutting curves

11305 Views 39 Replies 15 Participants Last post by DesertRatTom, Mar 30, 2018

456GTM

Discussion Starter · Jan 30, 2018

Hello,

I am planning to build two subwoofer "cabinets" for my electrostatic panels. I visited a CNC shop but they specialize in volume so I decided to do it myself.

I tried cutting the curved panels with a jig saw set at 0 [disabled rotation mode] but it turns a little bit no matter how tight I hold the handle. The chaps at the CNC shop recommended that I use a portable router. I had a top of the line Craftsman router but sold it many years ago so I just purchased a new Makita RT0701CX3 1-1/4 HP Compact Router Kit that comes with a straight guide.

My question is, how do it follow the curves with my new router? I have to make four pieces that have to be identical. Please see drawing. I have also attached photos of a friend's unfinished cabinets without the grille, they were built in a shop in the UK.

Best regards,

Horacio

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456GTM

Discussion Starter · #21 · Feb 6, 2018

Thanks Eric, you are right the T101AD was a poor choice. I found a T144D in a drawer, tried it and it worked perfectly. Nevertheless, per your suggestion, I will order a package of T244D.
Photo shows 3/4" plywood template, I will use the Freud top bearing bit that I received today to clean it up.

In '85 had a top of the line Craftsman, I do not remember the model, and made perfect circles using a Craftsman trammel point. There is one for sale on ebay but the distance between the rods that attach to the router base are too wide [5"] for my Makita. Festool sells a simple trammel unit [483922] for $27 but I am not sure it will fit my router. I will need a trammel to cut the drivers' holes [loudspeakers] at 277mm - inner circle. Please see template.

Cheers,

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Job and Knock

· #22 · Feb 6, 2018

456GTM said:
I found a T144D in a drawer, tried it and it worked perfectly. Nevertheless, per your suggestion, I will order a package of T244D.

If it isn't broke, don't fix it. If the T144D works for you then keep going with it.

456GTM said:
In '85 had a top of the line Craftsman, I do not remember the model, and made perfect circles using a Craftsman trammel point. There is one for sale on ebay but the distance between the rods that attach to the router base are too wide [5"] for my Makita. Festool sells a simple trammel unit [483922] for $27 but I am not sure it will fit my router. I will need a trammel to cut the drivers' holes [loudspeakers] at 277mm - inner circle. Please see template.

Looking at the CX3 kit it appears to have the plunge base. That plunge base uses a 8mm fence rods (I have the RT0700 kit over here complete with all 4 bases) which is the same size of fence rod used by Festool (for the OF1010), deWalt (DW613/DW615/DW621/DW622), Trend (T5), etc. So a trammel point such as the Trend BEAM/005 (see attached pic) will work on one of your fence rods or a complete trammel arm and point such as the Trend BEAM/001 or the deWalt DE6905 will work on one of your fence rods. Personally, being a cheapskate, I'd tend to opt for an offcut of thin plywood with the router screwed to one end and a veneer pin or thin screw driven through at an appropriate distance from the cutter to do a "home-baked" trammel. Don't really know about the Festool - the only one I've seen is a sort of guide rail adaptor/trammel head which requires two bars in the router. If that's the one you are referring to it won't work because the fence rod centres aren't compatible with the Makita. Personally I prefer the separate trammel head as it is more flexible - want a longer rod? Just buy a piece of 8mm diameter silver steel rod and cut to length

Edit: Just found the Festool SZ-OF 1000 and that should also work

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MT Stringer

· #23 · Feb 6, 2018

+1 What Eric said.
Here is an example...

456GTM

Discussion Starter · #24 · Feb 7, 2018

Trend Beams are only available in the UK, too bad I like them. I think that I will go with the homemade trammel posted by Mike.

On another note, I used the Makita with the top bearing flush bit for a couple of inches to see how it worked but I burned the material, I used a piece of poor quality Home Depot 3/4" plywood. What am I doing wrong?

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Job and Knock

· #25 · Feb 7, 2018

I'd be trying to leave a little less waste than that for the router, however, what speed are you running the router at? Also do you have any dust extraction on and how fast are you feeding the router? I suspect that you may be spinning the cutter too fast and without dust extraction and that your feed speed may be too low

456GTM

Discussion Starter · #26 · Feb 7, 2018

No, I do not have any dust extraction, I work in my garage driveway. Speed was at 6 - 30K rpm. Oliver and Mike suggested 1/8" excess but I will try to leave less.

Job and Knock

· #27 · Feb 7, 2018

I'd try reducing your cutter speed to more like 25,000rpm ("5") and increase the rate at which you feed the router into the work a little to see if that helps. 1/8in waste is fine (sorry, couldn't see how much it was).

456GTM

Discussion Starter · #28 · Feb 7, 2018

One more question, please. What bit should I use for cutting the holes? I understand that I should be passing the router in 1/8" increments.

Cheers,

Horacio

Job and Knock

· #29 · Feb 7, 2018

I think you need to get a bit which is configured for plunging entry. These often have a small piece of pointed carbide brazed in the very bottom of the cutter, For trammel work I'd use a 2-flute straight cutter. A lot of ordinary 2-flute straight cutters are plunge-type cutters these days

Rebelwork Woodworking

· #30 · Feb 18, 2018 (Edited)

Try a couple router dealers online. Read the information provided with bits on the page and see which bit meets your needs.. I do a lot of radius work and generally stick with Amana...

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456GTM

Discussion Starter · #31 · Mar 2, 2018

Jack, congratulations, what a great job you have done. I did purchase a pair of Amana 2-flute straight bit from Toolstoday at a very good price, cheaper than Diablo at the HD, they are fantastic.

Following the advise of everyone here I was able to cut a perfect template with a top bearing flush trim bit and also a perfect hole for the speakers, these are samples just to practice. Now I am ready to start the real work but I am having trouble with the rabbeting bit, please see photos. It seems that I do not know how to handle the router. I used this bit forty years ago when I built my first pair of speakers, it is a Craftsman and it is burned but I used it to practice.

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woodknots

· #32 · Mar 2, 2018

Horacio - I'd have to ask what direction you were routing - you should be going clockwise but it looks like the bit was pulling away from the edge which might indicate you were going in the wrong direction.

Semipro

· #33 · Mar 2, 2018

Agree with Vince you should be going clock wise, also you are cutting to deep a rabbet in one pass start with a larger bearing then switch to smaller bearing till you reach the depth you want.

456GTM

Discussion Starter · #34 · Mar 3, 2018

I passed it clockwise but as I said, the bit is over 40 years old, it uses screws instead of bearings. I should have thrown it away a long time ago but since I found it I used it to practice. I think that the screw does not have the versatility and free movement of a bearing, I will buy a Multi-Rabbet bit with four and six different rabbet depths.

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456GTM

Discussion Starter · #35 · Mar 3, 2018 (Edited)

The depth for the speaker frame is only 3.5mm but the width is 19.05mm or 3/4". The cut widths are between 1/8" to 1/2" max. How do I reach 3/4", any suggestions?

Many thanks in advance.

Horacio Vignale

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Stick486

· #36 · Mar 3, 2018

there are bits that will cut what you need..
https://www.amazon.com/Whiteside-Ro...=2025&creative=165953&creativeASIN=B01LXIM0YH
https://www.infinitytools.com/mega-rabbet-router-bit-and-bearing-set

..

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Cherryville Chuck

· #37 · Mar 4, 2018

If you plan on using this type bit a lot I would get it in 1/2” shank and replaceable carbide cutting edges ( an RC model). It’s a fair bit more money up front but will save you money in the long run.

456GTM

Discussion Starter · #38 · Mar 5, 2018

My router will accept only a 3/8" shank maximum

456GTM

Discussion Starter · #39 · Mar 30, 2018 (Edited)

Hello Chaps,

Attached are photos of my cabinets, they are far from finished, the base of the electrostatic panels need to be covered probably with pieces of kerf MDF and later veneered, they also need to be stained.

Per Jack's recommendations I bought several Amana router bits, they are great and a good value for the money, I purchased them from Toolstoday, I am very satisfied with their attention and customer support.

Horacio

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DesertRatTom

· #40 · Mar 30, 2018

Pretty nice case work. Got me wondering what happened to my rabbet set?

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