Line boring guide
How to Line Bore: Portable Line Boring Setup and Instructions
How to center the boring bar, mount the bearings, install the Power Feed, cut the bore and set the final size. Written by IRM for our Set A and Set B, and useful for most portable line boring setups.
- From the people who design and build the sets
- 26 years building line boring sets in Chicago
- Questions? Call and talk to Anguel
What You Need
What is line boring?
Line boring re-machines worn holes that sit in line with each other, so they're round and in line again. With a portable line boring set, the bar mounts right on the part, so the repair is done on site instead of replacing the part or sending it out. Below is how to line bore with one of our sets, step by step.
- Construction equipment / bucket repair
- Farming equipment
- Clevis plate bores
- Gearbox parts + housing
- Driveshaft housing
- Valves
- Elevator sheave housings + motors
- Shipbuilding applications
Line boring equipment you'll need
Everything on this list except the welder and the drill comes in our Set A and Set B. The Power Feed is an optional add-on.
- Boring bar with square tool ports
- Bearings and channel or plate
- Mounting legs and standoffs
- Centering cones
- Clamping collet with jacking screws
- Tool bits
- Measuring tools
- A welder to weld the legs in place
- A drive: the Power Feed with a handheld drill, or a MAG drill
Setup
How to set up a line boring bar
These steps are for IRM Set A and Set B (1.5" and 1.75" bars) with the Power Feed. The cones center the bar in the bores, and the bearings hold it there once the legs are welded.
Safety first. Wear safety glasses, and keep hands, hair and loose clothing clear of the turning bar. Follow the safety instructions for your welder and drill.
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Center the bar in the bores
- Take the shaft, cones, channels and bearings out of the set.
- Put the shaft through the first bore. Slide the channel and bearing assemblies onto it, between the two bores, then push the shaft through the second bore.
- Put a cone on each end of the shaft and push them into the bores. This centers the shaft.
- On one side, secure the cone tight against the bore.
- On the other side, place the clamping collet behind the flat side of the cone and tighten it. Then tighten the jacking screw to hold the shaft in position.
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Mount the bearings
- Attach four mounting legs to a channel and bearing assembly with set screws.
- Push the assembly against the surface around the bore. Tighten the set screw on the bearing against the shaft to lock the assembly in position.
- Do the same with the second channel and bearing assembly at the other bore.
- Weld the legs to the surface around each bore.
- Remove the cones.
Aligning with an indicator? Do it now, before you attach the Power Feed and the third bearing. Use the two bearings and the jacking screws on the assemblies to adjust the shaft.
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Add the outer bearing
- On the side opposite the Power Feed, mount a bearing on another channel with the mounting screws.
- Attach the remaining four legs, slide the assembly onto the shaft with the bearing facing away from the bore, and weld the legs to the surface.
- The other end of the shaft, the shank side, is where the Power Feed goes.
Power Feed
How to install the line boring Power Feed
The Power Feed mounts on a plate at the shank end of the bar and runs on a standard handheld drill. More about the Power Feed.
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Set up the plate
- Take the plate off the Power Feed by removing its four bolts.
- Install the four studs on the plate with the hex and flathead screws. Screw a ⅝” bolt, with its lock nut, onto each stud.
- Slide the plate onto the shaft on the shank side, with the studs facing the bore.
- Slide the third bearing onto the shaft against the plate and tighten its two mounting screws. The plate and bearing should slide easily along the shaft.
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Weld the plate in place
- Push the assembly toward the bore so the bolt heads sit flush against the surface, and tighten one set screw on the bearing.
- If a bolt doesn't reach the surface, loosen its lock nut, turn the ⅝” bolt out until it touches, and retighten the lock nut.
- Weld the bolt heads to the surface. Weld only two opposite sides of each hex, not all six.
- Loosen the mounting screws and remove the bearing.
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Free the shaft and attach the drive
- Remove all the set screws from every bearing. The only set screw left on the shaft should be the one for the tool bit. Check that the shaft moves freely through the bearings.
- Put the Power Feed back on the plate on the shank side.
- Install the driver on top of the Power Feed and attach it to the shaft. Crank the Power Feed by hand to make sure the shaft slides through the bearings.
Using a MAG drill instead? You can drive the bar with the MAG drill you already have and feed it by hand, which works well for lighter or occasional jobs. Call (224) 435-6999 and we'll go through the setup for your drill.
Cutting
Cutting the bore
Install the tool bit in a square tool port on the shaft and start cutting.
- Take smaller cutsDon't overload the tool bit with big cuts. Decide how much to take off on each pass.
- Keep bits sharpDon't cut with a dull tool bit. Always make sure it's sharp.
- Support long bitsIf the tool bit sticks out far from the shaft, support it with the clamping collet to prevent chatter.
- Keep the feed steadyThe Power Feed advances the cutter at a steady rate, so you can watch the cut instead of feeding by hand.
See more line boring videos on our YouTube channel.
Final Size
How to measure the bore and set the final cut
Our bars have square tool ports every 2.5” or 3”, so you can measure the bore without pulling the shaft out. Measure, then move the tool bit by the difference for the final cut.
- Measure the boreUse a Starrett 823 inside micrometer, or a dial caliper with extended inside jaws, with the bar in place.
- Move the bit by the differenceThe bit moves on the radius, so the bore diameter changes by twice what you move the bit.
- Lock it and finishRetighten the tool bit's set screw, check that it didn't move, and take the finish cut.
BoreRight Tool Adjuster
Moves the tool bit with a jacking screw and shows it on a dial, for setting the cutter on the final cut. Works on any line boring bar. See BoreRight
Modified Dial Caliper
Dial caliper with extended inside jaws to measure the bore while the bar is in place. See add-ons
Tool Positioner
Shows tool position in 0.001" increments (radius), 0.002" (diameter); for precise cutting setup. Minimum bore diameter: 2.5”
Troubleshooting
Common line boring problems
The tool bit is chattering
If the bit sticks out far from the shaft, support it with the clamping collet. Make sure the bit is sharp, and take smaller cuts.
The shaft won't slide through the bearings
Check for a set screw left on a bearing. Before cutting, remove every set screw from the bearings. The only one left on the shaft should be the tool bit's.
A Power Feed bolt doesn't reach the surface
Loosen the lock nut on that stud, turn the ⅝” bolt out until it touches the surface, and retighten the lock nut before welding.
I need the bar aligned more precisely
Indicate the bar before you attach the Power Feed and the third bearing. Use the two bearings and the jacking screws on the assemblies to adjust the shaft.
I need to cut a snap ring groove
Use the Inner Grooving and Bore Measuring Tool: a spring-loaded insert for cutting snap ring grooves that can be swapped with a gauge to measure bores. See add-ons
FAQ
Common questions
What is line boring?
Line boring re-machines worn holes that sit in line with each other, like the pin bores on a bucket or a clevis plate, so they're round and in line again. A portable line boring set mounts on the part, so the work is done on site.
Can I line bore with a MAG drill?
Yes. You can drive the bar with a MAG drill and feed it by hand, which works well for lighter or occasional jobs. The Power Feed is for longer bores, harder materials, or when you want a hands-free, consistent feed.
Can I line bore with a regular hand drill?
Yes, with the Power Feed. It works with various motor types, including standard handheld drills. See the Power Feed.
Do I have to weld anything?
Yes. The legs on the bearing assemblies are welded to the surface around the bore. With the Power Feed, the bolt heads on its plate are welded too, on two opposite sides only.
How do I measure the bore without taking the bar out?
Measure through the square tool ports on the bar with an inside micrometer, or use a dial caliper with extended inside jaws.
Does this guide work with other line boring equipment?
The steps are written for IRM Set A and Set B. Most portable line boring setups work in a similar way, but follow your manufacturer's instructions for their equipment. BoreRight works on any line boring bar.
Can I call with questions?
Yes. Call (224) 435-6999 for direct support from the people who build the sets.
This guide is general information for IRM line boring sets. Every job is different, so use your own judgment, follow safe shop practices, and keep within what the equipment is built for. Overloading the bar, bearings or tool bits can damage them. IRM isn't responsible for injury or damage caused by misuse, modification or overloading. If you're not sure about a job, call us first.
Need a line boring set?
Complete sets from $2,900, designed and manufactured in Chicago. Tell us your bore size and job, and Anguel will get back to you.
Ask a Question
Tell us your bore size and job. Anguel will get back to you.
- Prefer to talk? (224) 435-6999
- Helpful to include Bore size, distance between bores, and the equipment you're repairing.
- Built in Chicago Designed and manufactured by IRM. Sets from $2,900.