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FBoykin 01-04-2018 01:39 PM

Using a Makita 3-3/8" saw to re-groove teak seams?
Hi All, I'm about to tackle re-grooving the teak deck seams on a new-to-me GB 42 I bought in Oct. 2015. There are plenty of posts here and on the Grand Banks Owners site and I'm reading all I can. For now I'm trying to find some details on using the small Makita battery powered saw to deepen the seams. I'm hoping some folks can help me out.

I've seen posts on making a shoe for the saw and adding a 1/4 bolt or nylon dowel at the back end to use as a guide pin. Folks also talk about stacking multiple blades to cut a wider groove (1/4" width).

My questions (which I've also posted on the GB site) are:

How many teeth on the blade (regular cut vs fine cut, etc.)?
What kind of spacers to use?
Any tricks to stacking the blades besides making sure the teeth are offset? I believe you also have to remove the blade guard too.
Is the need for a "shoe" just to create a surface to attach the guide pin to?
Any details on what to make the shoe out of (plywood, lexan, etc.) and how big to make it? Same size as the saw base, etc.?

Luckily the Teak Decking Systems factory is on my drive to my boat - I've visited and talked w/them numerous times and bought their tools and caulk. Good folks.

Any tips or guidance on using the Makita to do the seams would be greatly appreciated. Thanks!

caltexflanc 01-04-2018 06:33 PM

What you want for that job is a Fein Multimaster with the fitting that is purpose-designed for this very job.... and you do NOT want to try and deepen the seams, especially with a saw, unless you are a top tier master craftsman (which given the post, I assume you are not). Personally, using a saw seems like a Really Bad Idea to me.

FBoykin 01-04-2018 06:39 PM

I've got the Fein tool and it is excellent. I'm not bad with a regular size circular saw and the Makita is quite small in comparison. Plus I plan to practice on a lot of scrap lumber before I try my decks. I think I can handle it - I'm pretty handy with tools.

But it never, ever hurts to ask questions and seek advice. Thanks.

Duvie 01-04-2018 06:43 PM

Most of the small battery saws I have used turn too slowly to give nice finished results and accuracy. I used to have the 3 inch old 9 volt makita which I found particularly slow running and difficult to obtain finished results

C lectric 01-04-2018 06:53 PM

The new 3" saws are a far cry from that old saw. Maybe still not the right tool, I don't know so no comment for this application.

Benthic2 01-04-2018 07:02 PM

Could you use a dremel tool and a metal straight edge ?

HopCar 01-04-2018 11:04 PM

Since youíre so close to Teak Decking Systems, I think you should be talking to them, not us. You are planing to use their calking compound arenít you?

Why do you feel the need to cut the grooves deeper?

Iím no expert, but Iíd be inclined to try it with a router, not a saw.

BruceK 01-05-2018 01:28 AM


Originally Posted by HopCar (Post 623248)
...Iím no expert, but Iíd be inclined to try it with a router, not a saw.

Before I decided my teak was past rejuvenation and needed new teak I explored the router idea. Problem seemed to be securing the router to precisely recut the groove.
A screwdriver, maybe bent to create a scraper, might work, after running a blade down either side of the caulk. The degraded condition of the caulk may come in handy.

Benthic2 01-05-2018 03:35 AM

is this what you're trying to do...

gaston 01-05-2018 04:15 AM

Silicone removal tools come in handy .Many different shapes and sizes .

alormaria 01-05-2018 08:08 AM

When I need to re-groove teak deck planks I use a small very sharp chisel, a straight edge, a very sharp utility knife and I take my time. Power tools are great when the wood is off the boat as in replacing a piece of decking. Never tried that Fein tool though.

DHeckrotte 01-05-2018 10:51 AM

2 Attachment(s)
Jig. Edge guide. Depth guide. Seeing as you go. Tight quarters. Dust in the face.

Given that the Teak veneer on our decks was only 3/8" thick and already grooved about 3/16", and the screws and bungs are about 3/16" down, I really wonder about wholesale regrooving. Maybe a little touch up here and there for aesthetics at badly worn spots.

I think I'd lean toward some sort of router for regrooving/cutting wood. I have a laminate trimmer which as a small motor and base. I recently saw pics of a large Dremel kitted out with a router blade and base - even smaller.

If you're trying to replace failed sealant, then I suspect knives, chisels and scrapers would be a far better thing. Plus time. The chisels and scrapers would be made to the correct width.

And, perhaps the 'knife' could be doubled to do both edges at once. The bevel - cutting edge - could not be symmetrical, but should be on one face (like a broad axe vs an ordinary axe). Here's a multiply-bladed knife, a tape slitter, that I cobbled together to cut 1" tape into 1/5" tapes for my purpose. I could imagine a two-bladed knife made with ordinary Stanley blades, instead of the dainty little Exacto #11s.

Nomad Willy 01-05-2018 03:43 PM

I think the blade you should have is a “dado” blade.
It’s a blade for cutting knotches for interlocked 90 degree jionts. Only straight not “tailed”.

Oh I see it’s a deck job. Are all the edge seams far enough away from cabin ect to give clearence for the saw?
You must also probably take into consideration the curve of the deck planks. Where the seams curve the kerk you cut w the saw will be wider than where they are straight. It will be dificult to keep from wandering as you go along. So your saw kerf may not be very smooth or fair.

Have you considered a router?

Greatlaker221 01-05-2018 04:35 PM


Originally Posted by Benthic2 (Post 623279)
is this what you're trying to do...

Really nice video. I liked the sweater, what was she talking about?:rofl:

FBoykin 01-05-2018 04:48 PM

I really appreciate the interest and the comments. The previous owner sanded the decks a bit "too much" and there are a number of popped bungs w/screw heads showing. That usually indicates the deck seam is probably now too shallow and needs to be re-grooved. Most of the seams are still tight so I'm thinking I'll try just re-grooving (if needed) where I replace the caulk that's come loose.

The Teak Decking System (TDS) folks and others say to stay away from a router as it's too easy for it to get away from you. They recommend a minimum seam depth of 1/4" - so I don't expect to have to cut very deep w/the saw. Set it for a 1/4" depth and it will actually cut probably 1/8" or less of teak.

A dado blade set would be perfect, but they don't make one for that size blade. I'll need to do what others have done and make one up on my own.

I posted my questions to the Grand Banks section of this forum to see if anyone on the site had some experience w/this job on their Grand Banks. It's not uncommon to need to do this if the decks have been sanded over the years. My boat's teak is still thick and in good enough shape to re-work the seams and replace the missing bungs. The TDS folks say their caulk will last for years. This isn't going to be a fun job, but I'm sure I can do it if I take my time. I'm retired...

There are plenty of posts about re-grooving teak decks over on the Grand Banks Owners site, but it's not as active as it used to be and most of the posts are some years old. I'm still researching this project and looking to see if I can find someone who's done this recently. Thanks for all the replies.

nauticlew 01-05-2018 05:20 PM

I have found a router is the best tool to remove the joint seal PROVIDED the router is in a guide. The concept is the same as the router guide used recess hinges on a door. I constructed a large guide 30" x 9" with stops in all four directions to restrict movement of the router base. The opening into which the router bit extended was not in the center but close to one side so the guide could be turned to get close to the edge. Note: some hand work is required to clean up along the edges and the ends. I aligned the guide and used body weight to hold it in position which cutting. I used the same technique to route out whole areas where the teak was split or damaged, to about 3/16" deep. If the repair is short it looks better to butt the end rather than make a caulked joint.

Bernie 01-06-2018 01:03 AM

The Fien Multimaster. You can clean the seams in 1/3rd the time with fewe or no mistakes. Finish the cleaning with sandpaper wrapped around a paint stir stick.

firstbase 01-06-2018 07:34 AM

I have the Fein, awesome tool as everyone knows. The hardest part of the teak caulking blades is swallowing your price and going ahead and purchasing them despite their stupid price. Ridiculous but they are the only show in town as far as I can tell.

FBoykin 01-06-2018 02:08 PM

I agree. The Fein is one very nice tool and I wish I had started using it years ago. And I did splurge on the caulk removal blade. All their blades are expensive compared to substitutes. I used the Fein a few months ago while replacing my sanitation hoses. The original hoses were 17 years old and you could smell them. They were stiff as a board and impossible to remove from the fittings. I got a Fein depth stop to keep from cutting through the fittings and cut the old hose up in pieces. Turned a very difficult task into a breeze.

But sometimes the Fein blade was cutting in a tough spot and my face and hands were pretty close. I decided then and there that the price of an original Fein blade was worth it.

However, I'm still looking for any comments from anyone who's ever used the Makita to deepen their teak seams. The Fein doesn't really work for that. Thanks.

firstbase 01-06-2018 02:53 PM

One of the boats I looked at before I bought the one I have had tired teak decks in need of complete renovation. One of my hesitations was the possible need to deepen the seams. I investigated the subject much like you are. Then, armed with the knowledge, I went to look at the boat again. I stood there staring at the seams imagining myself guiding a saw or router up and down all of the seams. Could I accomplish that without a mistake which would result in a nasty scare in the deck. I am brave to the point of stupid but I had to say no way on that project. Just can't see doing it all without error. The other thing was the time and place obsticle. Even if I committed to the time I have no way of doing it under cover without paying a bazillion dollars for a shed somewhere. So, I passed on thinking I could do that project even piecemeal. Ended up passing on the boat for this and some other reasons.

I believe it was Mr. Lowe over on the GB Owners forum who described how to build a shoe for a Makita to do this project. Did you find that thread? May have even been my thread. side note, you are correct, that forum has really slowed down, almost to a halt. Not sure why....

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