Category Archives: Tool builds improvements and repairs

Building a Gantry Crane lift

While restoring my Bridgeport Series I milling machine I reached a point where I needed a gantry crane to lift off the largest component from the mill. I shopped around online but could not find exactly what I wanted/needed in terms of size and capacity. This unavailability lead to me building one. Building yourself a gantry crane has the big advantage of being exactly the size you need. I wanted mine to be able to lift 2 tons safely, and fit with only an inch or so to spare inside my shop’s ceiling.

Drawing of the upright with dimensions. I used 0.120″ wall square steel tubing for the upright construction.

Harbor Freight does offer a reasonably affordable Gantry Crane. With a 25% off coupon you can get it for just under $600. I went and measured it to see if it would meet my needs. You can see my photos of measurements taken on the HF gantry crane in the gallery below. Turns out it would need a lot of modifications to be useful to me. I decided it wasn’t worth buying it to modify as making one would be less work and less money out of pocket.

After CADing up my proposed design, I went to my favorite steel supply shop Cohen Steel to purchase the necessary materials. All of the upright tubing is 0.120″ wall square tube. I ended up getting a short 4ft cheap W8x13 beam from their drop rack saved myself money. I plan to buy a 9ft beam length in the future to use this gantry crane to lift heavy things into the back of my truck.

CNC machining the mounting threads into the Gantry Crane Top Beam.

I machined the top brackets for the uprights as well as the beam ends on my CNC mill. The beam machining was a bit ridiculous, but I was lazy and this was the easiest way. You can see that most of it is hanging off the CNC mill’s table in the photo above. I had to pull the vise to do the machining.

This is the mounting plate drawing for the top of the uprights.

Above is the drawing for the mounting plate on the top of the upright. It’s certainly possible to make one of these with just a drill press and carefully center punching and laying out the hole locations. I used slots in my design as I will likely use different beam sizes when I go to a longer beam. I wanted to leave some wiggle and adjustment room to make assembly easier. The big hole in the bracket is there for alignment. I plan to weld locating rings or disks onto the ends of the beam to aid in assembly. The design of the upright mount is is such that I can add an extension to raise the beam height in the future if I need an extra few feet. Bolt on extensions are a lot easier than going for a telescoping upright design.

CNC milling the top upright mount brackets to secure the beam in place.

About the only trick I used in this build was tack welding the corners of two 0.25″ thick upright top mounting plates together before machining. Doing both at the same time saves some setup and machining time. If you look carefully you can see the tack welds in the corners. I later rounded the corners by hand and removed the tack welds separating the plates.

There was a lot of cutting on my band saw, grinding with different wheels, and welding to build this, but not a lot of tricks outside of being careful. WIP pics in the gallery below for your viewing pleasure.

When you are working long hard 16 hour days, trying to get a job done in a weekend, you make mistakes. I was working fast, and so focused on getting the base cross piece perfectly square that on the second upright I ended up knocking it off center. Thus the two sides are not exactly the same. In function this doesn’t change much, however it does irk me to have made this mistake in my exhaustion.

My whoops on this project, I didn’t notice it until way too late to fix it. Since it doesn’t affect the performance or use of the gantry crane, I left it to remind myself to be more careful in the future. This upright has the center post off center by about 2 inches.

Below is the picture of the gantry crane set up for the first time. I was pretty excited to get it together. It was late Sunday night and I still had a bunch of welding to do. I did a test fit without the top plate gussets or welds being complete to ensure it was going to work before I finished up the welding.

First test assembly of the Gantry Crane

For now, the uprights have a wheel on only one end. I used wheels from an old 4 ton jack I had scrapped a few years ago. You can see my water jet brackets and a fixed wheel test fit in the photo below. The axle is a piece of 3/4″ steel shaft on the Gantry lift. The screwdriver was just to hold it for photographic purposes. To date I have used my machine skates for the other side of the Gantry crane uprights in order to wheel it about under load. Eventually I’ll mount the spinning caster type wheels that you can barely see in the bottom left of the picture below to the other end of the uprights.

Test fit of the water jet cut brackets for the wheel mount. I designed it so I could tilt the upright and roll it about somewhat easily. Each upright is over 100lbs, not so heavy I can’t carry it around but it’s easier to be able to wheel them around.

For the lifting I have a 1 ton Chain Hoist and a Harbor Freight beam trolley. I regret using the trolley. I will eventually buy or make a static clamp type mount for the chain hoist. It tends to roll when in use, which I don’t like. Alternatively I may just make clamps for the edge of the beam to stop the trolley from rolling.

Beam trolley on the Gantry Crane, in use lifting the knee off the Bridgeport.

The gantry crane lifted the knee off my Bridgeport with ease. It allowed me to remove it safely, lifting it straight up slowly so I could ensure there would be no damage to the precious precision machined surfaces of the ways. You can read more and see photos about this first use of the gantry crane in my previous blog post: Bridgeport Milling machine Restoration: Part 3 Challenges of taking apart the mill

If you end up building a gantry crane and my post was helpful please share a picture of your project in the comments. I would love to see what I might have helped inspire you to build. Cheers!

Bridgeport Milling machine Restoration: Part 3 Challenges of taking apart the mill

A Series I Bridgeport is not all that heavy a piece of machinery, weighing in at ~2200 lbs. However, disassembly requires some careful handling as several of the individual pieces weigh more than a couple hundred pounds. The Knee is the heaviest, followed by the Ram. These two parts are too heavy to remove by lifting off the machine by hand, even with help. An accidental whoops with either could damage the ways or dovetails. You do not want to hurt these precision surfaces on your machine. Be sure to use safe rigging to lift heavy components. In my case I built myself a gantry crane to lift the knee, and used the knee to lift the ram.

Inevitably you will have problems getting something apart as part of your rebuild. I had several serious issues with mine. Long ago someone had broken the Ram Pinion Handle off the Mill leaving the broken stud threaded in the pinion. The Ram was very stuck in place from not having moved in countless years. I ended up pulling the Ram Pinion and using the old weld a nut onto the broken stud trick to carefully extract the broken threaded section. After letting the weld cool fully the broken stud came right out with a wrench. I will have to make, or buy, a new handle for the pinion.

Welding a nut onto a broken stud (if you are careful and good with your welder) is a great way to remove the broken section. This is a classic trick ,the heat burns off any varnish, thermal expansion must break siezed rusted bits, and the threaded section always comes out easily afterward. Use caution if into Aluminum, Magnisium, pot metals, etc. You can melt and ruin these metals quick if you aren’t careful with heat control.

The ram itself was very seized in place from minor corrosion. Thankfully my ram has some inner ribs evenly spaced inside the ram. One rib was not too far from the back of the column on the body. I used a 4ft heavy pry bar with a block of wood to spread the load on the metal. I was able to slowly wiggle the ram free by applying a large leverage force this way. I only did this after a week of soaking the ram joints daily with both PB Blaster and Liquid Wrench spray. It’s best not to rush these sorts of things, you don’t want to break your mill’s castings trying to free up a stuck major component like the ram.

Sliding the Ram off the machine onto a wooden support spacer after freeing up the ramwith a 4 ft pry bar.

I ended up using the Knee to remove the Ram after working it free. I built a wooden support box to gain the required height I needed. I used 2×8 lumber scraps to build a knee length support for the ram. This allowed me to slide it out onto the wood and use the z axis to get the height perfect and take all load off of the dovetails as I pulled it forward onto the wooden blocking. This went well, but I will put it back together using the gantry lift now that I have it.

I ended up building myself a Gantry lift to remove the knee. I felt using the forks on my tractor was not controlled enough. I didn’t feel an engine hoist was going to fit in the space I had, nor did I believe I could lift high enough with the one I can borrow. Plus I’ve needed a gantry lift a few times in the recent past. I decided this was the perfect time to build myself one. You can see the full weekend build of the Gantry Crane Lift in the separate blog post where I share my designs and lots of build photos. It was a long weekend but I managed to complete it in just the one so I could keep moving forward on the Bridgeport Restoration. Sometimes it’s easy to get sidetracked or derailed on larger projects like this Bridgeport Restoration.

I was fortunate in removing the knee from the mill, the gibb came free easily. I have read this is a real headache for some restorations. Again, lots of penetrating oil soaking in here since I first got the machine was likely helpful. I sprayed it often and heavily for a few months. Pulling the knee with the Gantry Lift was safe, easy, and prevented any possible harm to the critical precision surfaces on my mill. I have no regrets building the tool to do this correctly.

The red arrow points to the one part I seriously struggled with removing as part of this rebuild. The stupid Z axis gearshaft clutch insert. This part is supposed to just slide out with a tight fit, I had to torch the hell out of it, apply gear puller bending forces, and hit it with a large lead hammer to free it up. It was glued in place by old cutting fluid or oils that had varnished into some sort of solid resinous adhesive holding it in place.

If you are familiar with restoring old machines or engines you will understand that no rebuild ever happens without something being so stuck you feel like getting it apart is beyond all hope. We have all been there. Those of us who rebuild and restore things often have been there many times. For me, on this Bridgeport restoration, it was the removal of part number 85 on the basic machine drawing (code number 2060079 ), the Gearshaft Clutch Insert. The lil bastard of a part(shown in the photo above) was essentially glued in place by old oil or cutting fluid that had varnished to a solid strong glue. After checking every possible online reference and looking for weird variations of Series I mills to ensure I wasn’t going to break this component with some judicial application of brute force. I applied a ridiculous amount of force with a gear puller, used a torch to make it glow red hot, and then hit it hard with a 3 lb lead hammer repeatedly. This was after several less brutal attempts at removing the stuck component, and weeks of soaking with oils, solvents, and so on.

Once I pulled the stuck Z axis clutch mount off the gearshaft that lifts and lowers the knee, the rest of the parts inside the knee came apart quite easily. The shaft bearings are quite good. I’m not sure if the oils dripping down on them has kept the grease soft, but these ones do not need to be pulled apart, cleaned and repacked based on how nicely they turn by hand off the machine. I removed all of the components off of the knee for the rebuild. The gears, nuts handles etc all will get cleaned, buffed, and oiled before reassembly.

Remember, when you are stuck, take a step back. Turn to the internet and find whatever images, videos, forum posts, and online friends you can to help you work through whatever is stuck. Don’t immediately go for the I have to cut it off or destroy the part brutal approach. While it’s true some times that is the only way, more often than not there is a trick that will get the job done. Step back, sleep on it, and then revisit the problem another day with a fresh perspective. If you do this , you can almost always successfully remove whatever bitch of a component that is being a real bear and not coming apart for you .

“Bridgeport Milling machine Restoration: Part 2 – rebuild reference materials

This page is for me, I have learned not to rely on the internet to keep a history of files and documents I might need in regards to restoration projects, as often sites are taken down and things lost. I will upload a few useful documents and store some links that are very helpful for anyone planning to restore or work on a Bridgeport Series I Mill.

One of the challenges of bringing a Bridgeport Mill home is finding a space for it in your shop. This was my originally planned, but it really did not fit or work with the rest of my shop layout. Not to mention I couldn’t fit my car in the garage any more with it here.

This is a section of PDF’s I’ve collected that have useful information

The parts diagrams in the manuals are priceless for knowing what goes wear, as well as understanding how things come apart. You will reference these drawings an awful lot in your Mill rebuild.

This section is a list of useful links to helpful rebuild information, and or parts suppliers.

Rockford Ball Screw kit:

All the Series I parts:

Hardinge Parts for knee mills:

The final resting place of my Bridgeport. In the end I had to part with a shelving unit and clean a lot of stuff up to make a large enough space for the Mill to operate fully. Moving this around is not simple. I will likely put it on a leveling caster type base after I strip and paint it.

This page will likely see a lot of additions as I finish up my rebuild, but I don’t plan to keep links current, if a link is dead let me know and I’ll test/remove it when I have a moment.

Bridgeport Milling Machine Restoration: Part 1 Getting your Bridgeport home

At my day job, we have a Free or For Sale Slack channel. I visit this channel whenever there are new posts, but try hard not to claim anything I don’t absolutely need as I have enough junk. One day I saw a post by my friend and colleague of four years Scott where he was listing some machines including a craftsman lathe, a giant band saw, a huge 3 phase dust collector, and a Bridgeport Series 1 Milling Machine. I ignored his post the first time, but when he reposted a few days later, I asked Scott for more information. I have always wanted a Bridgeport, I told him I might be interested in giving his machine a good home if the price was right. Well he came back with the photo below and said, “the price is FREE!”. That’s my favorite price, but as my old mentor Donald Sundberg used to say often, There is no such thing as a Free Lunch.” So I asked, “What’s the catch?”

Many years ago Scott lived with a bunch of friends in an industrial space and they had a full shop they had put together. Apparently they had stored all of their large tools at Industrial Labs in Cambridge when they left this maker space home. This corner of the loading doc area at Industry Labs, is where the Bridgeport Mill sat for many years until I rescued it. I bet you are thinking, “gee that looks rusty…” right? I thought the same. I was willing to go look at it in person to see how bad the damage was to see if was possible to save this piece of old iron. Turns out, it was not that rusty at all. Rather it was coated with reddish wood sawdust on top of a hefty coat of way oil or grease they slathered over all of the surfaces. Which isn’t to say the machine was pristine or like new underneath, but it was a very restorable specimen. The years of shop dust, oil, varnished cutting fluid, and who knows what else had protected the metal underneath reasonably well. That and the hard chromed ways had me confident it would become a valuable addition to my home shop.

I wish I had taken more photos of the move itself, the reason the mill was free was because of the challenges of moving it. Apparently they had talked to Riggers, the cost was $3-5K. The loading dock was an old wooden terrible shape construction, the parking lot to it was on a hill, and there was ZERO possibility to get a rented dock height truck in to retrieve it. The loading doc was also damn tall at something like 46″ off the ground. I needed a way to wheel the mill from the dock onto my truck. Enter the first major challenge of this project, I needed a lift platform in the bed of my pickup truck. I did some math, made a few sketches, and stopped at Cohen Steel on the way home and bought the steel tubing needed to build one. I had a very short time to rescue the mill before Industry Labs was going to send it to the scrap yard for recycling.

After building the lift platform (construction photos above) with four scissor jacks welded for vertical adjustments I was committed to getting this machine home. I outlined a plan, and enlisted two friends Mike and Max from work to go over at 9am in the morning and help me load the machine. We were in a hurry, and sadly I didn’t take any pictures of the moving process itself. I wanted to remove weight from the top end, so I pulled the motor, the drive assembly, the head, and the head adapter. The table was previously removed and in storage along with some of the finicky bits, the DRO system, and some tooling. I would meet up with Alex to retrieve these parts later on. With the top end parts removed, We lifted it off the 4×4 wooden blocks with a pallet jack and with a hefty doc plate wheeled it into the blocked truck onto the platform I built adjusted to be perfectly level with the loading dock. I didn’t want the suspension to compress so I supported the frame with additional jacks.

Bridgeport Mill on Adjustable height loading platform in pickup Truck for transportation.

The loading onto the truck went surprisingly well, with the only issue being the truck was on a hill, even though I had driven the front tires up on boards to try and level it we had a minor scare. As the pallet jack rolled onto the lift platform it wanted to accelerate and keep rolling on it’s own. We managed to muscle it in place and drop it over the center line of the axle safely without incident. On the other end, unloading would go much more smoothly, as I planned to use the forks on the front end loader to just pick it up out of the truck.

Using the Forks to lift the Bridgeport Milling Machine out of the truck.

Note the blocked tailgate, I lifted the truck up with the jack so that the suspension wouldn’t make it harder to pick up the mill. Using a front end loader is not like using a forklift, the forks lift in an arc, which adds some additional challenges.

With the mill unloaded I left it just inside the Garage door. My car slept outside for a week, while I figured out where the Bridgeport would live permanently.

The only thing I did on the first evening owning the mill home was to spray some WD40 onto a rag and wipe down a few spots. The dusty goo on the mill was resilient but did come off with a bit of elbow grease and a lot of WD40 to reveal the nice shiny surfaces you can see in the photos below. I was happy I wasn’t wrong about the condition of the ways.

I’m going to close this first part of my Bridgeport restoration posts with these last words of wisdom. Taking a large machine like this mill home yourself is feasible, but only if you have the experience and equipment to do it SAFELY. The most important thing when moving large equipment is safety. If you aren’t 100% certain you can move it safely, hire someone to do it for you. In my day job, I am a mixed bag industrial engineer and research scientist. I have lots of experience and have moved equipment as large as 16 tons successfully without incident. It’s very easy to lose a life or limb when moving big machinery, and nothing is worth that sort of accident.