# Flattening hand plane with bridgeport mill?



## Thorbjorn88 (Jan 4, 2018)

A local community workshop has a bridgeport mill which I recently took a class to learn how to use for fun. I was thinking of things I could do with it and I thought of my Stanley no7 type 11 that is not quite flat and was wondering if anyone has ever tried or seen someone flatten the sole of a hand plane with a milling machine. What do you think? Is this a dumb idea? If you've tried it I'd love to see how someone mounted the plane to the milling machine.

I don't know exactly in what way my 7 is out of flat I'll have to pull out some feeler gauges when I get around to it, but I've always been able to get boards straighter with my Veritas LAJ or my 18" krenov than with my no 7.


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## SMP (Aug 29, 2018)

Easiest way is draw some sharpie lines across from side to side every inch or 2. Stick some 100ish grit sandpaper on a flat surface like a table saw or granite tile, then run the bottom of the plane back and forth a few times. You'll see where the sharpie marks where off first. Now when you do this, you want it all setup and just raise the iron above the bottom, this way it is all tensioned.


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## JayT (May 6, 2012)

I use a mill to flatten off the soles of the planes I make and wouldn't even consider doing one of my vintage cast iron ones. Machining the cast iron is straight forward, but clamping 100 year old brittle iron could be an issue. You'd have to have a support block that pretty much exactly conforms to the interior of the plane to support it properly.

The other issue to me is that the mill leaves machining marks that must be removed. Taking those out is pretty much the same amount of work as just flattening the sole to begin with. A surface grinder would be the proper tool to flatten, IMHO. Still need support, but won't have the extra work after the machine is done. Cast iron sands easy enough that I wouldn't go to that extreme unless one was seriously warped.

I do my planes on a mill because A) they are steel soled, so much more difficult to sand and B) I'm removing other material more than just flattening at the same time.

Lastly, I've rarely run into a vintage plane that is so out of flat that I would feel it needs machined to perform properly. As long as the toe, heel and front of the mouth are nearly co-planar, then it's good to go.


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## therealSteveN (Oct 29, 2016)

"but I've always been able to get boards straighter with my Veritas LAJ or my 18" krenov than with my no 7"

The bed of the Verital LAJ and it's slightly longer length will assure it a smoother result. The 18" Krenov? Well the Hock blade alone is an easy answer, but I think you are expecting the same job from 3 different tools. They are different tools, because you use them for different needs. So there probably shouldn't be a whole lot of comparison, except they are all hand planes.

Fettling a hand plane, easier watched than typed out. I posted THIS video, because Chris talks about real life stuff, like how flat. He points out depends on what plane you are talking about…. He also points out the "critical areas" which really are the only places you need to worry about much. Which leads us to #1 on that list, right in front of the mouth is the most critical point, and flattening with a Bridegport will likely change the size, and shape of the mouth, and to some extent where it is. Most of this discussion is going to be about very small amounts of metal. This is why sandpaper works so well. The Bridgeport is awesome at taking off a lot of metal, no doubt flat and even, but here it will often take off too much metal.






I just use sheets of sandpaper, cheaper, and you don't have that lump from where it used to bend around the corner. Plus I just lay my paper flat no spray adhesive. It allows a lot more ease toward going through the grits. I always go through the grits up to at least 400. I've found the smaller scratch pattern left by finer grits gets rid of the large scratches left by course paper, and with the finer pattern left I see less rust.


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## sansoo22 (May 7, 2019)

I've restored several old Stanleys…at least a couple dozen or so by now…and never would have considered a mill. Mainly for the things Steven and JayT mentioned above. Without proper support I'd be afraid of cracking the casting. I love a good no 7 so that would make me very sad and angry. The mill may get punished for my stupidity and then I'm back to being sad and angry because i hit my mill with a hammer. See its a viscous cycle.

For flattening I draw a cross hatched pattern with a marker on all three sides of the body. I like the Milwaukee inkzall markers (think i spelled that right). I draw thick black lines on both sides of the mouth because this is a very critical point to have dead flat. I use a surface plate certified to be flat within like a ten thousandth of an inch or something crazy like that. So its stupid flat.

I don't even bother checking for high and low spots anymore tho. I've done enough of them I just go to work on some 60 grit. If it removed all the marker then awesome. If it did't then i go back to sanding. I go thru all the grits up to 320 or 400 checking the critical spots Steven mentioned between each grit. On larger planes this includes the toe, mouth, and heel. For smaller planes I pretty much flatten the whole thing. For planes in the 4 and 5 size range that could be used on a shooting board I use a Starret tool makers square and straight edge to get them super duper flat and square. Not all of them get this treatment. It just kind of depends how "true" the original casting is. They could all be done dead nuts flat and square but it could be a potentially large time investment.


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## Thorbjorn88 (Jan 4, 2018)

Yeah that's what I was kinda expect about it being a bad idea. I've fettled a few planes, but nothing bigger than a 5 so I was just looking to avoid the effort and come up with something to try with the mill. So I'll just have to put some elbow grease into it.



> The bed of the Verital LAJ and it s slightly longer length will assure it a smoother result. The 18" Krenov? Well the Hock blade alone is an easy answer, but I think you are expecting the same job from 3 different tools. They are different tools, because you use them for different needs. So there probably shouldn t be a whole lot of comparison, except they are all hand planes.
> 
> ...
> 
> - therealSteveN


As for the LAJ (15" sole), 18" krenov, and 7 being different tools for different jobs I agree and by no means do I use them interchangeably but edge jointing a 36" or shorter board is the area I'm making the comparison (I don't usually use my laj for this but have pulled it out when my 7 wasn't performing very well). So that's the task I'm comparing them on. FWIW I actually do have a hock iron in my 7.


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## MPython (Nov 30, 2018)

I hope I don't violate any forum rules by referencing another forum. If I do, I ask the Mods to delete this post.

There's a guy over on WoodNet Forums who goes by there handle "tablesawtom". For a number of years he had access to a surface grinder at his job and had a little side business of flattening hand planes for a small fee. He flattened several for me and did a great job. You might want to contact him and ask him how he fixtured the plane body to clamp it to the bed of the grinder. His technique would probably translate to a mill bed.


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## bandit571 (Jan 20, 2011)

Hmmm..wasn't going to but..

First off, save the feeler gauges for a mechanic, or machinist….otherwise, just put them back in the drawer.

Iron bodied planes do not warp…wood bodied ones will, LONG before the iron will. "Out of flat"? is from wear, from the plane being used for a few DECADES.

Easy test for flatness, as long as you have something flat to sit it on ( tablesaw top..): you will also need two fingers you can rely on….

One fingertip on each end…press down equally. Does the plane rock? 
Place the fingertips diagonally to each other, press down….does the plane rock, at all?
Repeat step 2, going with the diagonal from the other corners…Does the plane rock?

IF no to these three steps…put the bloody thing to work..it is not the planes fault..look in the mirror.

Have done a few HUNDRED plane rehabs, over the last few decades…..I go with what works.


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## HokieKen (Apr 14, 2015)

I've considered doing this and may yet  One could build a jig to hold planes easily enough. I would be more likely to clamp it up in a vise and use some jacks to ensure there wasn't any excess pressure applied and to support the the ends. Most importantly, I'd do the machining with a flycutter fed slowly and only taking .005-.010" cuts. Sandpaper on a flat surface is good enough for handplanes. But it ain't as much fun


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## sansoo22 (May 7, 2019)

> I ve considered doing this and may yet  One could build a jig to hold planes easily enough. I would be more likely to clamp it up in a vise and use some jacks to ensure there wasn t any excess pressure applied and to support the the ends. Most importantly, I d do the machining with a flycutter fed slowly and only taking .005-.010" cuts. Sandpaper on a flat surface is good enough for handplanes. But it ain t as much fun
> 
> - HokieKen


Had to refresh my memory what a flycutter was. Been a long time since i used a milling machine. Video I watched took a .005 cut and left virtually no tool marks. Now i really want to see you do this with a plane.


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## splintergroup (Jan 20, 2015)

It would be much better to use a surface grinder. Smoother, more precision, etc.


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## Andybb (Sep 30, 2016)

If I had just learned to use a milling machine I too would look for an excuse to use it but…. I don't know if you need that kind of precision. Sandpaper on a saw top or granite plate is a better. If you just want to use machinists tools then the surface grinder would be a better option.


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## HokieKen (Apr 14, 2015)

> I ve considered doing this and may yet  One could build a jig to hold planes easily enough. I would be more likely to clamp it up in a vise and use some jacks to ensure there wasn t any excess pressure applied and to support the the ends. Most importantly, I d do the machining with a flycutter fed slowly and only taking .005-.010" cuts. Sandpaper on a flat surface is good enough for handplanes. But it ain t as much fun
> 
> - HokieKen
> 
> ...


I'm in the last stages of getting my new (to me) knee mill set up in my shop at home and have at least one plane waiting for an overhaul so stay tuned in the near future for a blog post. And yes, you can achieve a spectacular finish with a flycutter on cast iron ;-)


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## sansoo22 (May 7, 2019)

Just for fun I wanted to see what level of flatness my planes put on a piece of wood cuz hey that's what they are for. Used a type 15 no 4 i just finished up. Then using the same machinist square i checked that plane with I decided to check the scrap piece of red oak. Have an 800 lumen light behind the Starrett 3020. The blade on that tool makers square is 1/16th thick and has to be leaned over slightly to get any light.










Not sure if this is considered flat or not but I'm happy with my methods. Kenny if i had access to, and skills to use, machinist tools i can guarantee i'd be doing the same thing. Then again if it worked I'd get carried away and all my smoothers would get the same treatment because I have that kind of OCD.


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## P89DC (Oct 1, 2017)

The right tool is a surface grinder not an end mill. I doubt an end mil will make things better and is more likely to make it worse. Use the end mill to make corrugated bottom.


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## Andybb (Sep 30, 2016)

> The right tool is a surface grinder not an end mill. I doubt an end mil will make things better and is more likely to make it worse. Use the end mill to make corrugated bottom.
> 
> - Eric


+1 As long as you have the measuring devices to properly indicate it and a way to make sure it's flat and square when the mag plate is activated. I just don't think machinist precision is required for woodworking tools as a rule. In fact, the tools you use to indicate it will tell you if its flat before you even start grinding on it. Sandpaper on a dead flat surface should really get the job done. "Half a thou" isn't a woodworking measurement.

But…it'd be fun to mill or surface grind it just for the Abom type experience. Try it on a plane you don't care about first. Let us know what happens.


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## SMP (Aug 29, 2018)

I'd be more interested in milling the sole and at least one sides dead 90 for shooting.


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## CaptainKlutz (Apr 23, 2014)

The challenge with milling cast iron is the grain structure is not uniform with pockets of carbon in the matrix. 
Cast iron tends to get 'gummy' or 'sticky' with high speed milling, and it is hard to shave off small amounts due the carbon acts like graphite lubricant. 
If need to remove 0.010" it mills ok, but remove only 0.001", um good luck? 
The pockets of carbon can be 0.001", and shallow cut tends to chatter with the carbon lubrication.

Why do you think in old times mfg used to scrape cast iron surfaces flat?

+1 Surface grinder is proper modern power tool.


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## Sylvain (Jul 23, 2011)

Before considering machining your plane, read this.


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## Thorbjorn88 (Jan 4, 2018)

Thanks for the input all. If I really feel like I want to use the mill for something I'll mess with a plane I don't care about.


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## AMZ (Jan 27, 2020)

First, for disclosure, I own a manufacturing plant, with a complete machine shop for production support. Through the years, I've employed machinists from low skill uo through tool maker. To flatten and square a plane sole correctly, is time consuming and requires more skill in set-up/fixturing, than the actual process. The preferential method is a grinder, but suffice to say, the grinder must have proper capacity (think back and forth travel needed for a #8), as well as correct grinding wheel for the plane.

I had one guy that was very skilled on a mill, and as I have several mills, one with sufficient movement, he did a plane for me on it. I gave it to him to flatten and square, thinking he would use the surface grinder, but he used a flycutter in the mill. It took much longer, but was flat and square. The surface looked like it was engine turned, but was smooth. All in all, from the time and skill needed for a mill, IMO, a surface grinder is a better choice, but skill is needed to properly fixture the plane.

Results? First, the guys that worked on my planes were very skilled. With a properly sharpened & set-up blade, performance was at least equal to current premium plane offerings, BUT, if I would apply the wages I paid, a new LN or LV would be cheaper. I would seriously consder if this activity is truly needed and if so, would it be better done, with a piece of float glass, with Sc paper attached, to just take care of bad/necessary spots.


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## HokieKen (Apr 14, 2015)

Very good points AMZ. And you're correct that fixturing and setup are 90% of the work. It is absolutely unnecessary to machine a hand plane. So I'm gonna do it ;-)


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## AMZ (Jan 27, 2020)

> Very good points AMZ. And you re correct that fixturing and setup are 90% of the work. It is absolutely unnecessary to machine a hand plane. So I m gonna do it ;-)
> 
> - HokieKen


If surface grinder or mill, jacks on toe & heel of plane (besides what is holding the plane, such as a vise), and above all, check table travel before you touch metal.


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## HokieKen (Apr 14, 2015)

And jacks horizontal between the cheeks in the vise to prevent breaking those…


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