Filing Machine

A filing machine or die filer, is just what it sounds like, a machine for filing. It its most basic form it is a table with a file that goes up and down. Despite the simplicity a high degree of precision is achievable making them popular among clock and model makers.

I have known of their existence since high school shop but I have wanted to build a one after watching the Clickspring YouTube channel about 5 years ago. After seeing Adam Savage showing off the one he build about a year ago it lit a fire under me to finally build my own.

The casting kit I used is available from Andy Lofquist of Metal Lathe Accessories. It is the same set of castings that was used by both Chris, from Clickspring, and Adam Savage for their machines.

There are other castings sets are available but of all of them the MLA design looked the most robust. I also liked that the yoke operated in a closed case with an oil bath.

The total cost of the project when all was said and done was around $300. This includes the casting kit and any of the materials I didn't have on hand.

At a minimum a lathe with a 9" swing and a table top milling machine is needed for the build. Access to a full size milling machine is extremely helpful.

The total time to build the machine was about 2 months from start to finish. I would estimate it took about 60-70 hours of actual construction time but I didn't really keep track.

The design is simple and relatively forgiving to build but it is a fairly involved project and would not necessarily recommend it as a beginner project.

Andy Lofquist, the owner of Metal Lathe Accessories, was a pleasure to work with. A few emails and a PayPal invoice later I had a set of castings for the MLA-18 Die Filer on my doorstep.

The basic kit includes a set of drawing, a piece of bar for the table support and castings for the main body, cover plate, table, and yoke. Andy also offers a hardware kit, bronze for the bearings and a casting for the pulley as add-ons. I got the hardware kit but opted to source the bronze and the pulley on my own.

The first thing I did after receiving the castings was to clean up any flash and high spots on the castings with a file. I then gave everything with the exception of the yoke a coat of paint. I used Rust-Oleum forest green. It ended up a little more "John Deer" green than I would have liked but I can live with it.

I painted before machining for a couple of reasons.

First, I had some other projects going on so I was not sure how long it would be before I started the project. My shop is in a stone basement so humidity is always an issue. I didn't want a lump of rust when I eventually did start.

Second, it would save some masking later on. Generally cast surfaces are painted and machined surfaces left bare. By painting before machining you are left with crisp lines between the painted and unpainted surfaces.

I started with the body. It is the largest of the castings and everything else will eventually mount to it.

The other builds that I found used a milling machine for machining the body. Unfortunately my little Atlas horizontal mill was not quite up to the task. Fortunately for me the castings were designed to be machined on a 9" lathe so I was able to use my 1959 Logan lathe for most of the machining.

I started by facing the bottom flat. The lug on the top of the casting is made long for clamping in a lathe chuck. The bottom was center drilled and then supported with a live center. The full surface was faced off until it was flat. I left the base flange a little thicker than the plans showed to save some machining time.

The casting was then reversed so that the top faced out. My 4-jaw chuck was just big enough to grip the outer edge of the bottom flange with the jaws reversed.

The excess material from the clamping lug was removed then the casting was drilled and bored to size. The actual size of the bore was not all that important since the bearings are turned to match the bores. Once I had bores that were straight with reasonably good surface finishes I stopped. My bores ended up just a bit smaller than the 7/8" called out in the drawings.

Next the casting was chucked on the outside of the shaft boss to machine the counterbore for the back plate. The counterbore does not need to be aligned to any of the other features for the machine to function. The main requirement was that it was concentric to the outside of the casting.

The build notes that come with the castings say that the cavity in some casting are not perfectly centered due to the core moving during the casting process. My casting can be counted among these. To account for this I enlarged the counterbore diameter by about 1/8". There is plenty of material in both the body and back plate castings so this is not a problem.

After some careful alignment the shaft bore was completed. Had I been more careful with my alignment when doing the counterbore I would have probably not needed to realign the casting.

I had to use my longest boring bar due to the base flange. Fortunately my 3/4" bar was just long enough and worked well without too much chatter.

The back plate casting is made intentionally thick to provide extra material for chucking.

The casting was set to run true in the 4-jaw with the front face out taking care to ensure the recess was centered. The front was faced until clean then the outside turned to match the body counter bore diameter. In my case it was 1/8" over the plan dimension. There was still plenty of material. The casting was then reversed and gripped on the machined surface to face the back plate to plan thickness.

A template was drawn up in CAD then printed to layout the bolt circle. The template was aligned to the back plate and the holes center punched through the template. This method is accurate enough here since the holes in the body will be match drilled from the cover. A match mark will be provided to ensure the cover can be replaced properly.

I don't have a counterbore for the cap screws but I had an end mill the right size. Unfortunately a drill press lacks the rigidity to use an end mill in this fashion so I got creative and used my lathe. The back plate was gripped in the 4-jaw and centered on one of the punch marks. The hole was then drilled and counterbored using an end mill. The back plate was re-center to complete each hole. It certainly took longer but it got the job done.

Once the back plate was finished the holes in the body could be match drilled. I aligned the back plate to the body then it was clamped in place. One of the holes was drilled and tapped. A socket head cap screws was screwed into this hole securing the back plate. With everything locked in place the remaining holes were drilled. The back plate was removed and the holes were tapped while still in the drill press.

I have to say that of all the materials I've tapped, cast iron is the most pleasant.

The crank disk was made from a chunk of 1144 steel I had on hand. It was first cut down on my band saw to reduce the amount to remove on the lathe.

The machining was very similar to the back plate. The block was clamped in the 4-jaw chuck where it was faced and machined to diameter. The center bore was then drilled and bored to size before reversing it to machine excess material from the back side. The hole for the crank pin was drilled and reamed in the lathe by offsetting the disk in the 4-jaw chuck.

The drill rods needed for the shaft and file rod was purchased off ebay for about $40. It was more than I really wanted to spend but the 36" lengths will leave me with quite a bit for other projects.

The shaft was made from a section of the 3/4" drill rod . One end was turned down for a tight clearance fit to the bore of the crank disk. It was then reversed in the chuck and faced to length. The last step was to machine the keyway. The plans call for a woodruff key. I substituted a 3/16" straight key since I don't have a woodruff key cutter. I used my Atlas horizontal mill to cut the keyway.

The crank pin was ground to length from a standard 1" long 1/4" dowel pin.

With everything done I secured the shaft to the crank disk with 648 Loctite. Once the Loctite was cured the crank disk was pinned to the shaft with a 1/16" roll pin.

I left the crank pin loose until after final assembly just in case I needed to reduce the thickness of the crank disk later.

The file rod was fairly straight forward to make. It started with a piece of 1/2" drill rod that was purchased at the same time as the material for the shaft. I started by facing the end of the rod and drilling the 1/4" hole that will eventually be used to holed the shank of the file.

The rod was then flipped and faced to length. A 1/4" hole in the bottom was then drilled clearing the chips frequently.

The flat at the top was machined using my Atlas horizontal mill.

The hole in the side that connects to the hole up from the bottom was also drilled in the mill. This hole is to prevent hydraulic lock. The oil bath will seep past the lower bearing and be otherwise trapped. The hole gives the oil a place to go. At assembly the side hole is pointed towards the yoke so that it gets a shot of oil at start up.

Now is a good tie to point out that I have used my 4-jaw chuck for virtually all of this project. My 3-jaw chuck has too much runout for this kind of work. Some day I'll pick up a better chuck but once you get the knack of centering in the 4-jaw it really doesn’t take that long.

The challenge of machining the yoke is to figure how to start. I actually jumped around a bit before I landed on a method that worked for me. I ended up using the lathe for the bulk material removal then my mill to square things up.

I started by roughly squaring up all of the surfaces that required machining in the lathe. I faced the ends first then the bottom and top. I then moved the block to the mill to bring everything to final dimension and cut the slot.

The yoke was returned to the lathe to drill, tap and counterbore the hole for the clamp screw. It was re-chucked again to bore the hole for the file rod.

The final step was to make the saw cut. I did this by hand. I could have used my band saw or a slitting saw in the mill but it would have taken longer to set it up than cutting by hand.

The slide block was made from a piece of bronze I had left over from another project. I squared it up in my mill checking the fit in the yoke until I had a smooth sliding fit. The block was then drilled and reamed to fit the crank pin.

Both the slide block and the yoke was worked with a file and some emery paper to remove any burrs and to get a good sliding fit.

The hat was aptly named for its appearance. It has two functions the first is to clamp the file to the file rod and the second is to shield the upper bearing from filings.

It was not all that hard to make but did take a while due to the amount of material that needed to be removed. It was made from a piece I pulled from my scrap bin. This project became a good place to use up some of the random pieces I accumulated over the years.

The block was clamped in the 4-jaw and the outer profile turned. Once done it was reversed and re-centered. The portion that was used for chucking was faced off and the bore completed. A milling bit was used as a boring bar. To finish the hat the underside of the rim recessed to reduce weight.

Once out of the lathe the hat was drilled and taped for the file clamp set screw.

I purchased the bearing materials from Granger. The price was slightly less than what MLA was charging and they offered cored bar that would save some machining time and reduce the waste.

Grainger PN 56FY20

Grainger PN 56FW04

I started with the upper file bore since it was slightly larger than the lower one. It would give me a second shot if I made it undersized. I had just enough material so played the odds were I could. I also started with the file rod bearings so that I could check the length required for the shaft bearing.

I started by turning the outside diameter to fit each of the bores. I will use Loctite to secure the bearings so I went for a close clearance fit. A press fit could have been used but leaves less room for error. Once the outside was fit to the body the inner bore of the bearing was drilled then bored to a close clearance fit with the file rod.

The main bearing was done pretty much the same way only I started with the bore then turned the outside to size. The cored bronze made this a quick job

A plug was made to go beneath the lower file rod bearing to keep the oil from leaking out the bottom of the body. It was a quick turning and boring job. I used steel but any material could have been used.

Once I had everything done and I checked all of the fits the bearings were secured in place with Loctite. I used the same 648 Loctite I used for the shaft. With so much area the regular red thread locker would have probably worked.

The plans call for brass but brass is expensive so I used steel. The plans also note that there should be a clearance between the cap and the file rod so there is no real advantage to using brass anyway.

The cap was made the same as the back plate and crank disk. The holes were laid out using a paper template just like the back plate. The holes were drilled before machining the extra material off the back of the cap to make clamping easier.

The counterbores for the mounting screws were then completed in the drill press. They were just drilled to size so the bottom of the holes are not flat bottom. This will not make that much difference in use.

An alignment plug was made to help keep the cap in place while match drilling the body. The mounting holes were drilled and tapped in the drill press.

One of the cool things about my Atlas drill press is that the return spring can be unlocked. This is handy for tapping since you can put a center in the chuck and use this to keep the tap straight while tapping. The weight of the quill gives just enough down pressure.

The last things left on the body are the holes for mounting the table and the holes for mounting the machine.

The two bosses for the table mounts first needed to be milled to the proper width. I did this in my horizontal mill. Once I had two parallel surfaces the correct width I laid out the two holes for the table supports. These holes were drilled and tapped in the drill press. A wood angle bracket was used to support the casting.

The end of the shaft boss was also trimmed to length at this time. The casting was actually not to bad in this area so I could have probably gotten away with just cleaning it up with a file.

The mounting holes were marked out on the bottom and drilled through. The plans call for spot facing the top of the holes so that the hold down bolts seat better. The amount of work involved is not really worth it right now. The through holes will work fine but I may revisit this in the future.

The table supports were an easy job compared to the work that was already completed. The only critical dimension is the spacing between holes which needs to be constant between both pieces.

The MLA kit comes with a piece of 1"x1/2" bar for the supports. This was cut to length then the two pieces clamped together in the 4-jaw and faced to length. The holes were laid out and center punched.

I drilled and counterbored the blocks in the lathe clamped to my face plate. Again, this method was used because I don't have a set of counterbores. A milling machine would have made this job almost trivial.

The plans call for rounded ends but I was anxious to get things done so this will wait for now.

As with the rest of this build it would have been nice to have a larger lathe to machine the table but in this case it was actually not too bad on my 9" lathe.

I used the method from the build notes that worked quite well. I started by drilling and tapping a 5/16"-18 hole in the center of the casting. This was used to clamp the table casting to the face plate using a threaded rod through the head stock.

The casting was first clamped to the face plate with the bottom facing out. The bottom and sides of the rim were machined to clean. The casting was then flipped to face the top surface. Wood blocks were used to provide clearance for the support lugs. An indicator was used to center the casting off the outer rim.

The outer faces of the lugs were machined in my Atlas mill. Both lugs were machined in the same setup to ensure that they were parallel. I needed to relocate the cutter on the arbor to face both lugs.

The holes for the supports were located then drilled and tapped using the drill press.

The last step was to drill out the center of the table then countersink the back side to provide clearance for the file when the table is tilted. I was just able to clamp the table in my 4-jaw chuck.

The last step was to put everything together. Everything was test fit along the way but it was nice to finally have everything together.

To keep the oil in the body the build notes recommend a gasket beneath the back plate. I used a Cricut to cut one out of craft paper from a paper bag. I could have cut it out by hand but the Cricut made it much easier and faster. It was given a liberal coat of oil before assembly.

There were a couple of felt washers included with the hardware kit to put under the cap. They act as wipers to keep the filings out of the top bearing. Only a quick trim was required to fit the cap.

The motor I'm using is ancient. It was picked up by my grand father somewhere along the way. As far as I can tell it was made it the 20s or 30s. It still works but it is heavy and big. I’ll probably replace it at some point.

The filer was attached to a piece of plywood with a couple of carriage bolts for testing. I'll probably make a better base at some point.

The last real step is to modify some files for use with in the filer. Unfortunately I was not able to find any files local that could be modified so they will have to be ordered. A round file that I already had was used to test the machine out.

So, as with any project there are things that didn't quite go as planned. I couldn’t really publish this without acknowledging the issues I had along the way so here are the things that didn’t go quite right.

Body: The counterbore for the back plate is not quite square to the body. Functionally it is fine but I notice it.

Back Plate: The counterbores for the caps crews ended up oversize. I don’t have a counterbore so I used a 5/16" end mill. The problem is without anything to guide it the end mill wandered around a bit and making the holes oversized. If I to do it again I would drill the counterbore almost to depth then use the end mill to flatten the bottom of the hole with the theory that the existing hole would help guide the end mill.

Crank Shaft: The plans call for a 1/16" roll pin to pin the crank disk to the shaft. The problem is my first attempt left me with the roll pin stuck halfway in and bent. I ended up installing another slightly larger roll pin. The old one was cut and filed flush. Functionally it is the same the only thing that was damaged was my pride.

Plug and Lower Bearing: I didn't quite move fast enough when I Loctited the bottom bearing and plug in place. It ended up just a little bit proud of the body. It is only noticeable on a hard flat surface. Once I attached it to a piece of plywood it was fine. I could probably grind it flush if it ever is a problem.

Final thoughts on the project: It ended up being far more involved and took much longer than I expected. If all you want is the tool just go out and find an old one and buy it. You will spend more money but far less time. That said if I had to do it again I would. It was a very enjoyable project which I learned a lot from.