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Homemade Punch Plate for Makita BO4900V 1/2 Sheet Sander

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Blog entry by Rich posted 12-03-2016 04:59 AM 1991 reads 0 times favorited 7 comments Add to Favorites Watch

I’m sold on Makita sanders. I’ve owned Porter Cable sanders going back decades. Is it that mine are old and tired, or is Makita superior? I don’ t know. I do know that these Makitas are real workhorses and the fact that even the fractional sheet models have dust collection makes them perfect for me.

I’m really impressed with the dust collection on the Makita RO sander model BO5041. I have a Jet dust collector and a shop vac, but I hate having a hose to deal with in addition to the power cord when I’m sanding large panels, like for my interior doors that I build. So, when a sander can do a decent job with just a collection bag attached, I really like it.

I wanted a 1/2 sheet sander for better flattening on large panels. The BO4900V fits the bill. But, unlike their 1/4 and 1/3 sheet sanders, it does not come with a punch plate. I have no idea why. To order one costs between $23 and $38. That’s not that much money, but before I ordered one, I wanted to try making my own. How hard can it be?

I took a 1/2 inch piece of baltic birch plywood, and used 1/4 inch MDF strips to trim the bed. I used plain old 1/4 inch dowel pins that I put in a drill and spun against 120 grit to put about a 30º shoulder on each to sharpen them. I used the sheet of punched paper that ships with the sander as a template, drilled the base and glued the pins in to make a punch plate.

Here it is:

It works great. That BO4900V sucks dust just as well as the random orbit sander. I wish it had a permanent cloth bag instead of the paper one, but it’s shown itself to be durable, and I just ordered five of them for about $15. Those should last me almost indefinitely.

— Rich

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner



7 comments so far

View John Smith's profile

John Smith

1491 posts in 368 days


#1 posted 03-14-2018 08:31 PM

Rich – I did not understand why you needed a punch plate as I have never used one…...
with your photo and description, I understand it is to punch holes in the paper so the dust collection works.
the other half sheet sanders I had were the vintage (1980s) Black n Decker and worked quite well
as they were used either in the open garage or outside and did not have the dust collection ability.
I have a couple of dust bags from the Porter Cable belt sanders that might fit with a little tweaking.
I can make the punch plate template now that I have the machine apart.
Thanks for the tutorial !!!

-- I started out with nothing in life ~ and still have most of it left.

View jimintx's profile

jimintx

858 posts in 1790 days


#2 posted 03-14-2018 09:18 PM

I am going to get one of these Makitas before long, and I will be making this punch plate. Many thanks!

-- Jim, Houston, TX

View MSquared's profile

MSquared

82 posts in 120 days


#3 posted 08-29-2018 09:33 PM

Thanks Rich, I’ll try that. I have my ‘80’s Makita Palm Sander punch plate around here somewhere! In the meantime, I improvise. Collector does work nicely still. Question; What’s the consensus of using 1/2 and 1/4 sheet sanders (and, are they truly ‘orbital’?) as opposed to round sheet orbital sanders? From what I’ve read, round orbital sanders give a better, less swirl-marked finish. True? To what degree?

-- Marty, Long Island, NY

View Rich's profile

Rich

3902 posts in 795 days


#4 posted 08-30-2018 04:24 AM

Marty, it’s a shame that orbital sanders (sheet sanders) have gotten such a bad reputation these days. As with any tool, they have their strong points and weak points.

Any sanding method leaves marks. The bottom line to getting a good finish is to have a smooth surface. The grit of sandpaper you can use between coats depends on the solids content of the finish and its ability to fill in the scratches left behind.

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

View MSquared's profile

MSquared

82 posts in 120 days


#5 posted 09-30-2018 05:52 AM

Thanks Rich. That being said, what is the measurement method/terminology of finish solids content?

-- Marty, Long Island, NY

View jimintx's profile

jimintx

858 posts in 1790 days


#6 posted 09-30-2018 04:12 PM

Thanks Rich. That being said, what is the measurement method/terminology of finish solids content?
- Squared

Here is what I think I know:
Solids content is the amount of solids left behind when the finish has dried. It is generally expressed as the Percent Solids. Expect that to be in the range of 15 to 40 percent of the finish as it comes out of the can as sold, but it could vary outside that range, too.

Higher solids content material is “thicker”. Thus it is slower to dry, and usually more difficult to apply. It can take twice as long for a 32% solids finish to dry, compared to a 16% solids finish. If you elect to add liquids to thin a finish, you are decreasing its solids content for application.

Here’s what I think this means: If you are using a thin, easy to flow finish, you might find you need to use a finer grit abrasive between coats to obtain the smooth finish you are seeking.
.

-- Jim, Houston, TX

View Rich's profile

Rich

3902 posts in 795 days


#7 posted 09-30-2018 05:49 PM


Thanks Rich. That being said, what is the measurement method/terminology of finish solids content?

- MSquared

Well, now that I read what I wrote back then, I don’t like it. It must have been late :)

The way I worded it seems to imply that you would choose your final grit of sandpaper based on some measurement of the solids in the finish. I don’t do it that way and I didn’t mean to imply it.

Jim pretty much summed it up. You can generally find the solids content listed on the MSDS. A higher number will build faster and fill scratches better. Take a Sher-Wood high solids lacquer for instance, the MSDS suggests sanding with 240 between coats. You don’t sand after the final coat.

However, I find it almost always necessary to do some rubbing on the final coat. That’s a topic in itself though.

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

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