How to create a square flat surface with limited tooling.

[Buzzkill]

I'm in the process of rebuilding my tire power hammer.  I acquired several pieces of 3/4" thick steel, which I have fastened together using full perimeter welds.  I now have a more or less solid chunk of steel to use for my anvil that is 5.5" x 5.25" x 29.5".   I need to clean up the ends that will be the mating surfaces for welding to the steel plate on the bottom and support bottom dies at the top.

I'm looking for suggestions to help me get flat surfaces on the ends that are square to the sides.  I do not have any milling equipment or anything else that can handle a nearly 250 pound chunk of steel.   Left to my own devices I'd probably end up using a 4.5" angle grinder, a carpenter's square, and copious amounts of verbal "encouragement" to get the result I'm looking for.  Any and all viable suggestions are welcome.

[anvil]

You about nailed it. Not sure if it will fit but sometimes a bigger grinder(diameter wheel) will give a flatter surface.  Also, if possible in your setup, for me, draw filing gets me the flattest in plane surface

[Frosty]

There are a couple "shade tree" methods that'll work. If you have a router make a router "sled" to keep the router 90* and using carbide bits take it to square a couple thousandths at a time. 

My #2 and less favorite would do the same thing using a carpenter's hand held belt sander. I don't know if metal cutting belts are available you might have to have some glued up. Once again you need to make the appropriate "sled".

I keep fresh sharp blades for my cutoff bandsaw that will cut straight and not pull for making the cuts as close to square as possible. Then I get to grind or file to true things up.

Frosty The Lucky.

[Buzzkill]

I think I picked up a router somewhere along the line, but I'm sure I don't have any carbide bits.  That still may be the best bet.

Surprisingly, or maybe not, I was noodling with an idea to build a frame to hold the angle grinder at a consistent depth.  Sounds like roughly the same idea, but using a router instead.

I'm assuming I set up the sled by using a level/square combination to make sure the router rides on rails that are as perfectly perpendicular to the sides as possible.

I'm thinking an angle iron framework with some adjustment screws in the corners.  Is there a better way to accomplish that?

[Frosty]

That's the basics of a router, etc. sled. Check out one of the wood table building channels like "Blacktail Studio" for examples. A plunge router adjusts depth easily and as precisely as you like. You'd need to buy appropriate bits, I can get mill bits that fit my plunge router.

I think a sled for a disk grinder would be pretty complicated, It'd need a larger gap for the disk to clear the sled frame and adjusting depth could get involved, I'd probably use shims. Of course the disk could float using the sled rails as the depth stop. 

An Oregon Mill is a good example of a sled with wide rails for clearance. 

I haven't actually "designed" as setup for truing up something like you project, I just know what device to make. I've seen some imaginative sleds, one on a home built saw mill that was made from steel pipe and gate rollers.

Frosty The Lucky.

[Goods]

When I’ve worked on getting something dead flat, I would use both an angle grinder and draw filler. Draw file, lightly grind the spots that are filed. Then beach to filing. This gets me down to the lowest spot faster the filing alone… Just have to be gentle with the grinder to avoid making new low spots!

Keep it fun,

David

[Buzzkill]

Thanks for the suggestions so far guys.  The tinkerer in me wants to build a sled system for a power tool, but the practical side of me is arguing that it's only 2 ends about 5.5" square.   I probably won't get a chance to get back to it before the weekend anyway, but it gives me something to think about in the meantime.

[Frosty]

You can mark high spots for further attention with a square and either a sharpy or by smoking the blade and marking it on both X & Y axis. 

If you have a surface plate it's as easy as laying a piece of carbon paper copy side up on the plate ad using a pair of squares lower the block onto the paper and give it a GENTLE tap with something ight like a wooden hammer handle. The high spots will be plainly marked. remember to lower and lift it straight up and down. No sliding around now, though that IS fun.

Frosty The Lucky.

[Buzzkill]

I'm leaning towards the router idea if I can find the router.  I think I bought one at an auction a few years ago.

It's doubtful that I could "gently" lower this block straight up and down on anything at this point.  I know I can't do it myself - even if I lift with the legs.

[Frosty]

Me either. Last router I picked up was at a yard/garage sale for under $20. I think it's collet will accept mill cutters, if not there are carbide router bits you'll need to go easy on. 

I'll give some thought to making an angle grinder sled easily adjustable. I use a cup wheel for precision grinding with angle grinders so clearance would be different. Guess it's time to get out the graph paper.

Frosty The Lucky. 

[anvil]

I think you are talking a metal block, correct? A router is really not the tool to use, guide or not. Its made for wood. You will fight it continually to keep it on the track. To apply enough down force to prevent this, you will burn your iron and/or burn up your router. I've done both. I used a router and a guide to get a level surface on half log treads for a iron sweep stairway and a router is great for this, but they aren't built to deal with metal, carbide or not. A file is a blacksmith tool which one of its primary purpose's is to do just what you'r doing. Create a flat plane. I call files a poor man's vertical mill,,,   

Again, a 4-1/2" side grinder makes it very hard to get a truly level surface. A 7" or 9" one works very well. Resurfaced a number of rebuilt and built up anvil surfaces with this tool.  

For such a small piece, just get a couple 3 10$ good quality metal files from fine to coarse and draw file it. Treat them well and they will last forever.

[Frosty]

Granted a router isn't intended to cut steel but done properly it'll work fine. Saying you need to apply downforce to keep it on the sled illustrates you aren't a machinist. The cutter  spins too fast to apply down force without breaking carbide or burning HSS steel cutters. To pull this off with a router it just needs to brush the surface to cut. It will true it up fast, much faster than filing and will require less skill.

Filing to flat and square involves more than one skill set. Been there done that, Jr. high metal shop 1 file test was to file 2, 3/4" cubes, everybody in the class made dice for no extra credit. The instructor graded with a micrometer and square.

Frosty The Lucky.

[Buzzkill]

Well, the nice thing about this for me is I have the router already (found it last night).  I bought it cheap with other tools at an auction, and I haven't needed it for anything else in the past couple years.  So, if the plan doesn't work or I destroy the router I'm really not out more than the carbide bits.  If that happens I can still go to plan B or C which involves some combination of angle grinders, files, levels, and squares.

I'll try to remember to report back here how it goes, but I probably won't get a chance to do anything more before the weekend - and even then it's a maybe thing.

[George N. M.]

One thought, bit rpm.  Generally, metal cutting uses a lower rpm or fpm than wood cutting, e.g. drill presses or band saws.  I do not know what rpm a cutting head on a lathe would run but it may be considerably slower than a router bit.  You may need to slow down the router with a rheostat to slow it to optimum cutting speeds.  Too fast a speed may cause chatter and gouging that will take a long time to correct with less aggressive methods.

Personally, I think I'd see if a local machine shop could mill the ends square.  IMO it would be worth the cost.

"By hammer and hand all arts do stand."

[NoGoodWithUsernames]

George has a good point with cutting speeds. Might be alleviated by using carbide as it generally wants higher feeds and speeds than something like HSS. 

Definitely check a feeds and speeds chart to see if you can get it in the ballpark when ordering a cutter.

[anvil]

Correct, Frosty, I'm not a machinist, I'm a blacksmith and this is a blacksmith site, not a machinist one. And I do have a fair amount of time running a file as both a Farrier and Blacksmith. Consider the mass of a vertical mill and the fact that you are moving the material into the tool vs a hand held light router that you are moving over the material. Consider that on the mill both the cutter and the material are firmly secured and you don't have to apply any manual force to do the job, much less the rpm difference between working wood or steel.  Did you forget this?  Seems that if you learned how to file a level  surface and file a cube in junior high, its not a majorly difficult task. Did you pass the test?

However, I agree with Buzzkill and giving it a try is most often the best way excepting jumping off bridges to see what happens.     But consider with a router you will need a guide to run on that will hold up to the downward force you will have to apply and a carbide bit. Both add time and cost to the job. Personally I think that using a hand held router will mess up your block without a major setup. If it were me and I didn't want to file it, I'd consider a hand held belt sander. A vice and a belt sander is all you would need. By the way, I'm assuming that by ends you mean 5.5"x5.25" and you are cutting off or dressing the weld bead.  

 

[Buzzkill]

anvil, George, and everyone else  I appreciate you voicing your opinions and concerns - that's exactly what I asked for.

If I use the router it will not be free-hand.  I will build a frame and sled mechanism from square tubing and/or angle iron to keep it square to the sides and limit motion in all directions except traversing the face of the block in a straight line.  If I use this method I will also use a rheostat controller to decrease the spindle speed.

I think overall it would be faster/more efficient to use a grinder and square to get close then draw file. I don't need precision measured in ten thousandths of an inch.  However, I see this as an opportunity to try something that may have applications for other projects in the future.

[Frosty]

Using a wood router to cut steel is indeed using it for something its not only not designed for but one it should never be asked to do. It's not quite breaking the rules but it's certainly bending them.

On further thought, just because I'd attempt this I realize it's not something I should've suggested. Perhaps use a high speed end grinding bit to finish it but I withdraw more.

Yes Anvil I passed the file section on the first check by the instructor and got a mention for it. I had an "unfair" advantage, my father was a machinist, I grew up in his shop and already had a solid grounding in precision work. I was the only one to smoke the pieces and wipe with a square so I could see the high spots and file appropriately. It wasn't easy, I'd never done something like it and Dad just laughed when I asked him how to tell me the easy way. 

If you use the grinder on it, the grit that gets embedded in the stock will dull the files very quickly, use old dull files until you're down to clean steel. Smoke it before filing and use the worn files till the smoke is gone, that should get you past the worst of the grit.

Frosty The Lucky.

[Irondragon Forge ClayWorks]

11 hours ago, anvil said:

. If it were me and I didn't want to file it, I'd consider a hand held belt sander

I agree and have used my Bearcat sander with 80 grit belt to level and square a lot of stock, of course using a square and calipers to check progress.

I can't control the wind, all I can do is adjust my sails.

[anvil]

Awesome, Frosty. I find it pretty cool that the Cal tech program for junior high had a test like that. Its not an easy task without quite a bit of filing experience. Especially considering that it was a test, back in the day, that apprentices had to do to become journeymen.

A huge boost to my filing skills came from Tom Joyce once when I worked for him. "You used to be a Farrier?" "Yes" " Then you must be pretty good with a file." It took about 6 months for that to soak in and realize that simple association. Sometimes we can't see the forest for the trees. Thats when I consciously added a file to my primary tools. I basically add a touch of the file to nearly everything I do. Works especially nice to add a bit of brightwork to the champfer on the edge of leaves. 

[Buzzkill]

On 8/7/2023 at 4:06 PM, Frosty said:

I use a cup wheel for precision grinding with angle grinders

The only cup wheels I found seem to be for masonry type of work.  Are those suitable for steel or is there another type of cup wheel that I overlooked?

[Frosty]

It was jr. high AKA Middle school standard metal shop class curriculum in the 60s. It was a different world in the 60s and 70s. Shop classes were all trade classes to give students a grounding in trade skills so hopefully graduates could find entry level jobs in a skilled occupation. At Dad's insistence I took metal shops, light and heavy through "Occupational heavy metal shop. Started an hour earlier than regular classes and lasted 3 hours/day. I graduated, certified in stick, mig and tig welding and with papers that would let me jump straight to advanced machine shop and light metal shop trade classes. Or apply as a "trained machine shop" employee. No machine shop hires a grad as trained face value of course but . . . 

Schools were in the business of training people how to work in a given line  of work back then.

Buzz: A search for "cup grinding wheels for steel" results in pages of hits for all size disk grinders.

Frosty The Lucky.

 

 

[Irondragon Forge ClayWorks]

If you are not removing a lot of material a flap disk on the angle grinder works pretty well.

I can't control the wind, all I can do is adjust my sails.

[anvil]

Just to add a little more confusion, I prefer a 9" cut off type wheel. Decades ago I worked as a welder boxing beams and used this to clean up the welds. Worked in the field and used the same tool.  I have rebuilt a couple 3 anvils by building up the face and had real good luck using this type wheel to get a level surface. In my shop I have little to no need for a grinder of any sort, so, thank my lucky stars my wheels last for decades.    I've not used a cup wheel for many things so can't compare them. I keep it real flat and can get a lot of wheel surface to contact the anvil face. For me, this large flat and parallel surface works a treat and is pretty quick. 

[Buzzkill]

21 hours ago, Frosty said:

Buzz: A search for "cup grinding wheels for steel" results in pages of hits for all size disk grinders.

Been there, done that.  If you actually click on them you'll find that most of them take you to cup wheels designed for masonry.  However, it looks like there are some called "flaring cup grinding wheels" that do indeed appear to be designed for metals.  Rather pricey though.  I'm still wondering if the cup wheels designed for masonry are effective if used on steel. I've used masonry cut off wheels on steel before and they don't work as well as those designed for steel, but they suffice in a pinch.