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How I Do Hand Plane Rehabs #6: Fixin' and Fittin' my Frog

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Blog entry by HokieKen posted 11-23-2016 05:55 PM 934 reads 1 time favorited 12 comments Add to Favorites Watch
« Part 5: Polishing and Refinishing Part 6 of How I Do Hand Plane Rehabs series Part 7: Working up the Iron »

Well, we’re done with the cosmetic stuff. Time to get down to the real nitty-gritty. Woo Hoo!

If you have an old plane that’s in decent enough shape that you don’t care to polish it up and there isn’t any significant rust, you can skip all of the previous work and start here. From here on is what really gets our plane in good working shape and takes a mediocre plane and makes it work better than new.

We’re going to focus on the frog mainly in this entry but you have to tune the fit with the sole so we’ll see the main body a bit too. I want to preface this by saying that this frog required more work than any other I have encountered. Its issues aren’t due to abuse by a previous owner but, and I DESPISE saying this about Millers Falls (and I’ve never had to before), just plain sorry machining and quality at the time of manufacture. In truth, this plane needs to be put on a mill and machined on both the frog and the base but, since most people don’t have that option and I’m not putting that kind of effort into a plane I don’t really have a specific purpose for, we’ll work with what we have.

The frog is arguably the most important part of the plane. It has to hold the iron firmly and with good support while still allowing it to be adjusted for depth and lateral alignment. In other words, it has to hold tight but not too tight. So, the first thing we’ll attend to is the bed where the iron seats.

The first thing I do is to make sure there isn’t a raised area around the threads for the lever cap. Usually at a minimum the lead thread is slightly raised. I take a small mill file and flatten that area. I pass the file over the entire face to make sure there aren’t any other raised areas as well. Then I lay the iron bed flat on my granite surface plate (table saw, float glass, jointer bed, granite/marble tile – use the flattest surface you have) and see if it rocks. Make sure the lateral lever and/or depth adjustment fork aren’t the culprit. No rock? Good. Now make sure you can’t see any light underneath and can’t slide feeler gauges under it. Just because the 4 corners are coplanar doesn’t mean there isn’t a hollow in the center and we want to whole surface flat.

This frog has a hollow in the middle. So, now we have a decision to make. We need to flatten this face. How? Well we can file it. However, that’s not the best way to flatten a surface. It can be done but usually requires removing more surface than necessary. It can be done to a frog with the lever and fork in place though.

Another option is to machine it. Not practical for most so we’ll not go that route either.

The best option for most of us is to lap it on a flat surface using some kind of abrasive. We’ll see how that’s done. However in order to do so, I need to get the lateral lever and depth fork out of the way because they stick up above the plane of the surface.

The lateral lever on this plane is different than most. Most have a peened brass or mild steel pin. This has basically that but instead of peening, it was deformed by some sort of punch. See the “X” mark in the end of the pin and the lever? I’ve never seen this method before but, it is quite effective evidently because this lever is not at all sloppy.

Now, I normally don’t remove the lever unless absolutely necessary but I will for this one. In fact it turns out to be quite easy. I just “wiggled” the lever side to side while pulling and it came off. Normally, you’ll have to take a small needle file and file the peened part back to the pin diameter to get the lever off. Keep in mind though, eventually you’re going to have to get the lever back on and retained so have a plan!

Now for the adjustment fork. Normally this isn’t a big problem. It’s just a pin through the casting with one side peened or mushroomed to give a press fit when driven in. Just use a punch and drive the pin out. Drive the small side though. If you use the punch on the wrong end, you risk cracking the casting. If it won’t drive easily, flip it over and try the other side.

This pin comes out easily but is a good, tight fit in the hole. Rather than driving it all the way out, I just move it far enough to get the fork off and leave it. It’s out of the way.

You’ll find that I use machinist layout fluid a lot. You can do without it but it’s not expensive and a bottle will last a LONG time. I’d recommend grabbing a bottle. It’s good for a lot of things. Here, I’ve painted a thin coat onto the iron bedding surface of the frog.

Now I’m going to lay the surface on a piece of 240 grit wet/dry paper on my granite plate, apply even pressure and stroke it back and forth 3 or 4 times.

This shows me clearly where the high spots are and where there is no contact. See the bright spots on the 4 corners and part of the left side? That’s where my iron would bed now.

I want the bed to be one big flat surface though. At a minimum, I want all 4 corners, and down both sides planar. I could live with a slight hollow in the center. But I’d prefer not to.

So now I’m going to take a piece of 320 grit wet/dry paper and my granite surface plate and work the surface until I clean all of my red dye up. I have to be sure I apply even pressure and don’t allow the frog to rock while I’m lapping it, particularly when you don’t have all 4 corners planar. I use good old WD-40 as lubricant when I use wet/dry paper.

It only took 10-15 strokes to get a good, continuous, flat surface. Note that this could be done on lapping plates, diamond plates, water stones or oil stones. Use what you have. Just make sure it’s flat. See how all my dye is gone? That’s good stuff ;-)

You can also see there are still tool marks from the machining on this face. I don’t mind. I have a solid surface for the iron to bed on and I have a little bit of friction. Like we said, needs to hold tight but not too tight. A little texture on the bed gives a little grip without deforming the iron.

One note about the iron bedding surface on frogs: Some frogs don’t have a flat surface for the iron but have a “web” cast in for this feature. The process is the same, just flatten the machined surfaces.

Now let’s turn our attention to the other side of the frog and where it mates to the body. What’s important here is that the frog sits solidly on the machined pads in the base. A frog that doesn’t can cause all kinds of problems that are hard to diagnose. It can cause the frog to shift a little in use giving the impression that the lateral alignment has been knocked off. It can cause chatter in the cut leading you to think the iron isn’t bedded well. It can also cause the iron bedding surface to be skewed in relation to the sole which can make alignment hard and leave one side of the cutter with less support than the other. Long-story-short, get this part right ;-)

The first thing I do is to lightly run a fine mill file over the machined pads to remove any burrs or raised areas. I also check with a straight edge to make sure the lower pads are aligned and the larger pad doesn’t have a hump in it. A slight hollow in the large pad is ok, it will allow for a little hump in the mating surface in the body which is harder to detect and correct while still giving solid contact.

Now the next thing to do is to check the fit with the base. Sit the frog in place and put pressure down with your fingers over the screw holes. Now apply some pressure to the back corners then the front corners, one at a time. The frog should set solidly no matter where you apply pressure. No? Well here comes the PITA part…

This frog doesn’t sit solidly at all. It has a very significant rocking action. Normally, I have to do little, if any, work on this fit. This is by far the worst I’ve seen. The hard part is that it’s very hard to gauge or work on the pads in the base because they’re not very accessible. The best solution is to take both the base and the frog and clean up all the pads on a mill. But that’s not practical for most, so let’s do it the hard way…

Remember my red layout dye? Well here she is again. I paint a thin coat on the machined pads of the base. And I mean THIN. If I put it on too thick, it won’t tell me what I need to know. It’s worth noting that Prussian Blue is a better option if you do this often. It’s thinner and non-drying. Layout dye works for me though and I have it on hand so I use it. I have to work fairly quickly though. It’s slow-drying, but it does dry. That’s fine for work like we did with the frog face but you can’t “print” mating parts if it’s dry.

Now this is critical… You have to be methodical and consistent in how you do this to get good results. I sit the frog straight down onto the pads with no pressure and pick it straight back up. I don’t want to rock it or press it down at all. If I do, I won’t be able to see the true contact areas. Here is where the dye transfers onto the frog:

We have dye transfer on both pads on the left side and a little bit on the right side right at the screw hole. Not even a hint of contact on the lower pad on the right side. Also, see the tool marks from machining on these pads? It’s horrible. You can’t really tell from pics but they are deep. I probably could have machined these surfaces just as well with an angle grinder. It’s not really a big problem in and of itself. But, the lack of contact on the lower right pad (which indicates the top pad and lower pads weren’t machined parallel to one another) coupled with the terrible finish is an indication of some very sloppy work by a machinist.

(Hops off of soapbox)

Now we have dye transfer showing us where our high spots are on the frog pads. I’m going to use a shopmade carbide scraper and just lightly scrape only the dyed spots to remove a little bit of material. You can do this with a small file as well. The key is only to remove the high spots – nothing else.

Now we’re going to dye the base pads again, re-print the frog and scrape away the high points. I didn’t take pics of the whole process but, I repeated about 7 or 8 times. I know I’m done when I print the frog and get this:

I then clean up all the dye off both pieces and do one final print just to be sure dye build-up wasn’t affecting my results. All’s good :-)

If we look closely after we finish the fitting process, we can see that I had to scrap far enough on the left side that I removed the machine tool marks. That’s a lot more work than you should have to do on most planes and more than I’ve ever had to do on any other one.

The frog fit still isn’t perfect. If I was starting over, I would have taken this body and frog and machined the mating surface. While I have solid contact with the body, the machining limits the amount of adjustability I have for the frog position.

When I set up a plane the first time, I usually try to start with the frog lined up with the back of the mouth. Then I can leave it there or move it further forward if I want to close the mouth up. But, when I set this frog, I can’t move it far enough back to align it with the back of the mouth because the machined faces in the base aren’t wide enough to accommodate the pads on the bottom of the frog. Not a deal-breaker by any means. But just another indication of some cost-cutting manufacturing on this plane.

This is the only later model Millers Falls plane I’ve had. It was made sometime in the 60’s or 70’s most likely. They left the red paint off, replaced all the brass with steel, switched from Cocobolo to Goncalo and replaced the trademark 3-point lever cap with a single piece. None of these things really affect the usability of the tool. However, after digging in a bit, it seems they also skimped on the quality of machining and fitting the tool at assembly. Fortunately, the castings seem to be same quality as their older planes and the iron and chip breaker seem to be unchanged.

I guess the point is, don’t seek out newer models of these vintage planes. Most people know that pre-war Stanleys are the better vintage for consistent quality. Apparently the same holds true with Millers Falls. Just a little nugget I thought I’d share ;-)

Wow, we can see the finish line! Now we just need to finish up with the main body and get our iron and chipbreaker in shape. Then we can re-assemble, fettle and make some shavings. I’ll try to wrap all that up next week. In the meantime, Happy Thanksgiving to all!

Thanks for reading, comments welcome as always!

-- Kenny, SW VA, Go Hokies!!!



12 comments so far

View Handtooler's profile

Handtooler

1465 posts in 1888 days


#1 posted 11-23-2016 10:07 PM

Most excellent educational communique I’ve ever read on the subject matter. Thanks for this in=depth coverage.

-- Russell Pitner Hixson, TN 37343 bassboy40@outlook.com

View ClutteredShop's profile

ClutteredShop

38 posts in 308 days


#2 posted 11-23-2016 11:01 PM

Very interesting and informative, but I have one question: First you flattened the base of the frog, then tested it with the dye against the bed, and then UNFLATTENED it so it would conform to the sloppiness of the bed. Since you used a scraper rather than I file, could you not have used it on the bed instead of on the frog? Yes, you achieved a good fit this way, but only for this frog on this bed. That frog can never be used with another bed, and vice-versa. I know that ordinarily one doesn’t switch these parts around, but I’d still like to hold the possibility open in case, for instance, I dropped the plane and cracked the base, I could still use the frog on another plane with a missing or defective frog.

-- Cluttered Shop

View HokieKen's profile

HokieKen

4117 posts in 894 days


#3 posted 11-24-2016 03:13 AM

ClutteredShop: Short answer is sorta:-/

You are right, this frog is specifically fitted to this base. If I want “plug and play”, I’m gonna need to machine both to ensure everything is flat and parallel and offset the same amount.

I think you may have misunderstood though, I didn’t actually flatten the botyom of the frog, only the top where the iron beds. On the bottom, I just made sure there were no burrs or raised “humps”. I also verified that the 2 lower pads were coplanar. I suspect the underlying issue was that even though they were, the plane they lay in was not parallel to the plane of the upper pad.

You are also correct that scraping the body would have been another way to skin the cat. The problem is the 2 lower pads on this plane are recessed. Even with a small scraper, working those would require more skill or patience than I posses ;-)

Thanks for bringing up those good points! The truth is though, most frogs can be fitted with little fuss to most bodies of the same period and maker. This plane is definitely the exception rather than the rule.

-- Kenny, SW VA, Go Hokies!!!

View HokieKen's profile

HokieKen

4117 posts in 894 days


#4 posted 11-24-2016 03:27 AM



Most excellent educational communique I ve ever read on the subject matter. Thanks for this in=depth coverage.

- Handtooler

Thanks Handtooler. Glad there’s an audience! :-)

-- Kenny, SW VA, Go Hokies!!!

View ClutteredShop's profile

ClutteredShop

38 posts in 308 days


#5 posted 11-24-2016 04:32 AM



ClutteredShop: Short answer is sorta:-/

You are right, this frog is specifically fitted to this base. If I want “plug and play”, I m gonna need to machine both to ensure everything is flat and parallel and offset the same amount.

I think you may have misunderstood though, I didn t actually flatten the botyom of the frog, only the top where the iron beds. On the bottom, I just made sure there were no burrs or raised “humps”. I also verified that the 2 lower pads were coplanar. I suspect the underlying issue was that even though they were, the plane they lay in was not parallel to the plane of the upper pad.

You are also correct that scraping the body would have been another way to skin the cat. The problem is the 2 lower pads on this plane are recessed. Even with a small scraper, working those would require more skill or patience than I posses ;-)

Thanks for bringing up those good points! The truth is though, most frogs can be fitted with little fuss to most bodies of the same period and maker. This plane is definitely the exception rather than the rule.

- HokieKen


Thanks for the clarification. I’ve restored (some of them quite minimally) maybe fifteen cast iron planes and have seen a lot of things that can be wrong with them, but one thing I haven’t run across is a frog that wouldn’t sit flat. I’m now working through your earlier posts in this series and enjoying learning new things and also enjoying the flashes of recognition when you mention something that exactly represents my experience.

-- Cluttered Shop

View maxhall's profile

maxhall

72 posts in 1957 days


#6 posted 11-24-2016 08:38 AM

Your attention to detail is top notch. Going to have to order myself some prussian blue.

View HokieKen's profile

HokieKen

4117 posts in 894 days


#7 posted 11-24-2016 12:45 PM



Your attention to detail is top notch. Going to have to order myself some prussian blue.

- maxhall

Make sure it’s the Permatex non drying stuff. There are a lot of artists paints sold in the color “prussian blue”. They won’t work;-p

Be aware the blue won’t help with things like flattening the iron bed because it’s non-drying. It’ll just wash off in your slurry. Grab some layout dye for that.

Also, if you need a scraper, get carbide. HSS will work on cast iron but not on some steels


Thanks for the clarification. I ve restored (some of them quite minimally) maybe fifteen cast iron planes and have seen a lot of things that can be wrong with them, but one thing I haven t run across is a frog that wouldn t sit flat. I m now working through your earlier posts in this series and enjoying learning new things and also enjoying the flashes of recognition when you mention something that exactly represents my experience.

- ClutteredShop

That’s great to hear! I hope this series, and my experiences can help some folks in some small way. I didn’t “invent” any of this stuff but hope to pass along the knowledge I’ve gleaned from others online over the past couple years. You’ve done more planes than me though, this will be 9 or 10 I’ve done. Maybe you should be the one writing the blog! :-)

-- Kenny, SW VA, Go Hokies!!!

View ClutteredShop's profile

ClutteredShop

38 posts in 308 days


#8 posted 11-25-2016 05:09 AM


Thanks for the clarification. I ve restored (some of them quite minimally) maybe fifteen cast iron planes and have seen a lot of things that can be wrong with them, but one thing I haven t run across is a frog that

You ve done more planes than me though, this will be 9 or 10 I ve done. Maybe you should be the one writing the blog! :-)

- HokieKen


Thanks for the vote of confidence. I’m new to this forum, though, so I don’t yet know the rules about blogging.
There are a few contributions I could make that some people might find worth while if it’s ground you haven’t already covered. I could show how I restored a frog that had the back part snapped off, how I restored a couple of cracked totes and totes with chunks missing, and how I’ve closed the mouths of wooden planes. These were done before free photography came the the ClutteredShop, however, so I could only show “After” pictures, not “Before” and “During.”

-- Cluttered Shop

View HokieKen's profile

HokieKen

4117 posts in 894 days


#9 posted 11-26-2016 04:00 PM

ClutteredShop: I think you will find that Lumberjocks is a great place for sharing knowledge. Most folks on here are willing to give help and advice whenever they can and are truly receptive and appreciative when offered the same. Blog posts are a great way to give and recieve experience and skills. I’m sure any posts you make on the repairs you’ve done will be appreciated and well-recieved. Pictures are always helpful (at least to me) but definitely not necessary. I’d personally be interested in how you fixed the snapped frog!

-- Kenny, SW VA, Go Hokies!!!

View hnau's profile

hnau

88 posts in 298 days


#10 posted 11-30-2016 06:02 PM

-- Spammer in processed of being removed.

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bhuvi

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#11 posted 12-01-2016 02:02 PM

-- Do NOT click links. Spammer in the process of being removed.

View Roger's profile

Roger

20871 posts in 2560 days


#12 posted 12-18-2016 09:31 PM

I agree w/Russel up above. Thnx again for all you’ve put together here

-- Roger from KY. Work/Play/Travel Safe. Keep your dust collector fed. Kentuk55@yahoo.com

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