How to make a keyway in a hole. How to make a keyway on a lathe

Typically, a lathe is used for boring, threading, reaming, countersinking and drilling, but their capabilities do not end there. I propose to consider a way to use it to hollow out the keyway on the bushing. To do this, I use a 1K62 screw-cutting lathe.

Set of tools

To perform the work, in addition to the machine, you will need:

• boring cutter;
• slotting cutter;
• oil for lubrication.

Any boring tool can be used, of course, within the limits of the sleeve diameter. As for the slotting tool, its cross section is selected for the required width of the keyway. Lubricating oil is required only when working with hard metal. For mild steels, provided that high-quality cutters are used, it is not necessary, since chamfer boring and slotting does not cause critical overheating, which can accelerate the erasure of the cutting edge of the tool.

Preparatory stage

The bushing is installed in a three-jaw chuck. Before chiselling, you must first prepare its inner and outer chamfer with a boring tool. They are made only from the side from which the slotting tool will enter. This is the simplest process familiar even to an amateur turner, therefore it does not require separate consideration.

After preparing the chamfers on the machine, you need to set the minimum speed to prevent the spindle from scrolling. On many machines, the chuck can give backlash under load, so in this case it is necessary to put a spacer. To do this, a bolt with a nut of a suitable height is placed under it. When it is unscrewed, the length of the stop increases, so it is pressed tightly against the cartridge, thereby removing the rolling.

The grooving tool is slightly clamped in the tool holder. He sets the bushings in the center, after which it is necessary to make fine adjustments. To do this, it is inserted into the sleeve, moving longitudinally with the caliper along the sled. The resulting scratch should run along the sleeve bore from one edge to the other. In the cut line, there should not be an area without a scratch. If it is, then this is to talk about the presence of a bias. When the cutter is set correctly, it must be clamped very tightly, as the load during chiselling is much higher than when performing standard turning work.

Chiselling process

Since the bushing has its own radius inside, before starting to measure the depth of the groove, it is necessary to cut it off in order to get a flat area, which will be the zero reference point. To do this, with the help of a caliper, I move the cutter inside the sleeve along the longitudinal slide, removing the thinnest metal shavings. After it returns to its original position, I bring the cutting edge closer along the transverse slide to the body of the sleeve by 0.1 mm. Again I make a longitudinal movement along the carriage. I repeat the process until the gutter loses its radius. As soon as he leaves, this will be the zero point for reference.

Now I start chiseling the keyway. In my case, its depth should be 2.6 mm. Using 0.1 mm increments, it would take 26 cutter movements to reach this depth.

After deepening the groove by 2.6 mm, without changing the setting on the limb, make a few more repeated movements of the cutter to clean the plane from small burrs. Next, the sleeve is removed from the cartridge. Her second end is rather rough, but this is easily solved. The boring tool is again installed in the tool holder, and accurate chamfers are removed. After that, the sleeve can be used for its intended purpose.

Chiselling on a lathe is a lengthy, though not complicated process. In my case, the longitudinal movement of the caliper is motorized, so everything is done relatively quickly. It is also possible to gouge a groove on budget hand-operated machines, but in this case it will take much more time.

In the conditions of a home workshop without special machines and devices, perhaps only the so-called “collective farm” keyway can be performed: this is when a joint hole is drilled with an electric drill in a gear or pulley mounted on a shaft with a center on the circumference of the joining parts. Then a cylindrical key is inserted into this hole. But such a connection of parts is unreliable - after all, it is not without reason that it is not in any GOST.

For the manufacture of “GOST” keyways in detail, I developed a manual desktop machine (or, one might say, a device), which I have been using for several years now. I think that such a machine can be useful, like me, for home craftsmen, amateur designers, in a school workshop.

This hand-operated vertical planer is similar in design to a drilling machine, and in principle to a slotting machine.

The entire structure is assembled on a base measuring 350x350x20 mm. It (the base) is also a desktop on which there is a stand with all the nodes necessary for cutting paeov and a caliper with a three-jaw lathe chuck. The thickness of the base of my machine is 20 mm. At first it was a chipboard (as in the photo), but then I replaced it with a steel one with the same dimensions - the machine became more massive, but also more stable.

Here I will make an explanation: there are other differences in the drawings from the image of the machine in the photographs. The fact is that during operation it was revealed that some components and parts would be better done a little differently. And these improvements are reflected in the drawings.

1—base (steel plate s20); 2 - stand (steel, circle d40); 3 - support flange (steel); 4 - fastening the flange to the base (M12 screw, 3 pcs.); 5—holder (steel); 6 - holder stopper (M12 screw); 7 - axis of the lever rod (half of the M12 stud with a nut, 2 pcs.); 8—lever rod (steel strip 30×8, 2 pieces); 9 - swivel link with the lever (M12 bolt, 2 pcs.); 10 — lever (steel strip 30×8, 2 pieces); 11—compression spring; 12 - console; 13 - slider (M12 screw); 14—retainer (M12 screw); 15—mounting the lever on the axle (gun M12, 2 pcs.); 16 - axis of the handle (steel, circle 18); 17 — handle (pipe d30x18.5); 18 - mandrel-tool holder (steel, circle d64); 19 - cutter; 20 - stopper (M10 screw); 21—three-jaw lathe chuck: 22—caliper

Near one edge of the base, a stand is fixed by means of a flange - a steel rod with a diameter of 40 mm and a height of 450 mm. A longitudinal groove is cut along the entire rack, and a groove is made on one of the youths for joining with a flange. Now it became clear to me that it would be nice to make the rack even higher - up to 500 mm - it is often necessary when you need to make a groove in long (or high) parts (for example, hubs), then there is not enough console lift. The flange is a large stepped washer with a central post hole and three evenly spaced 12.5mm holes for attaching to the baseplate. Correspondingly located, but only M12 threaded holes are also made in the base table. The stand with a machined end is inserted into the central hole of the flange, and the parts are connected by welding, and after that the flange is screwed to the base.

A holder and a console with a compression spring between them are mounted on the rack in a sliding fit.

The holder is a rectangular parallelepiped with a small height, relative to the dimensions in the plan, with a central hole for the stand and three M12 threaded holes - two counter blind side holes and one through one of the ends. Of course, the definitions of "end" and "side" for such a geometric body are identical, but, I hope, are clear from the drawing. The locking screw of the holder is screwed into the end hole, and the studs, which serve as the axes of the lever rods, are screwed into the side holes.

The console is a more complicated detail. It consists of two hollow cylinders (rack-mount and mandrel), interconnected by a jumper made of a steel square pipe with dimensions 60x60x2.5 by welding. In the body of each of the cylinders, there is an M12 threaded hole: in the rack - for the fixing screw to keep it from turning, and in the mandrel - for the locking screw. In addition, a pair of M12 “half-studs” are welded to the rack cylinder in its middle from opposite sides (you can also use screws with the same thread) - they serve as axes for the tool feed levers.

1—rack cylinder (circle d80); 2—lintel (pipe 60x60x2.5); 3—mandrel cylinder (pipe 80×64); 4—lever axis (M12 pin, cut in half, 2 pcs.)

We must try to perform this operation as accurately as possible, so that subsequently, during operation, the levers do not warp, the holes in them do not break, and the axles themselves do not wear out. Therefore, before welding them, it is worth doing some technological operations. First, on the rack cylinder, it is necessary to mill (or grind off with a file) a pair of diametrically opposite flats measuring 20 × 20 mm. Holes with a diameter of 4 mm are drilled in the center of the flats on each side. Then they are drilled to a diameter of 6 mm with one installation with a drill of the required length. Axial holes of the same diameter are also made in both "half-studs" (screws). After that, a straight piece of wire of the same diameter is inserted into the holes of the cylinder. “Half-studs” are mounted on the protruding ends and are first tacked, and after aligning the position, they are finally welded to the cylinder. At the end of the operation, a piece of wire is knocked out.

The holder on the rack at the desired height is fixed with a locking screw and serves as a support for the entire tool feed mechanism: a console with a mandrel fixed in it with a cutting tool and a system of levers for its longitudinal feed. The console is lifted and held in the upper position by a spring. From turning on the rack, the console keeps the fixing screw, the end of which, sharpened for the corresponding profile, slides in the longitudinal groove of the rack. The rubbing surfaces of the parts are covered with a thin layer (like a firearm) of grease before work.

Mandrel - a part with which the tool or its holder is fixed in the console. In my case, the mandrel and tool holder are made of steel 45 as one piece in the form of a stepped cylinder with a diametrical hole for the cutter near the free thinner end. Here, a threaded hole M10 is drilled at the end - through it, the cutter is fixed in the hole of the tool holder with the corresponding screw. A flat is milled on a cylinder of a larger diameter - the M12 fixing screw rests against it, which does not allow the mandrel to rotate when a torque occurs from the cutter. The same screw keeps the mandrel from falling out of the console cylinder. But his efforts from squeezing the mandrel out of the cylinder during the working stroke may not be enough: for this, a shoulder is left on the mandrel.

The levers and rods are made of steel strip with a section of 30×8 mm. The levers are put on the axis of the mandrel cylinder of the console, and the rods are on the axis of the holder. Both those and others are fastened together by bolts-axes pivotally.

Between the upper (free) ends of the levers, the axis of the handle is inserted and fixed - a cylindrical rod with a diameter of 18 mm with an M12 thread on the end grooves. The handle itself, made in the form of a sleeve with a diameter of 30 × 18 mm, is loosely put on a greased axle. The surface of the bushing is knurled beforehand.

A special story about the machine support. Outwardly, it looks like a machine vice. And the workpieces for processing are fixed in a three-jaw chuck mounted on the upper movable platform of the caliper from a metal-cutting lathe. With the help of the caliper, the workpiece is fed relative to the cutting tool to the depth of cut. Looking ahead, I note that the depth of cut in one pass is quite small - only 0.2 - 0.3 mm.

The caliper consists of a welded body and a movable table. Although there are several elements of the body to be welded (5 pieces), they are quite simple - almost all (except for the racks) - in the form of rectangular parallelepipeds. Racks are made of equal-shelf steel rolling angle 40×40 with a half-cut vertical shelf. By the way, the traverses of the body and the cross member of the movable table are holders (bodies) from broken turning cutters. Whoever has a milling machine available will easily manufacture the body and platform as one piece from a massive workpiece.

1 — housing stand (corner 40×40 with cut vertical shelf, 2 pcs.); 2—body platform (steel, sheet s7); 3—front traverse (cutter holder); 4—rear traverse (cutter holder); 5—movable table (steel, sheet B7); 6—cross member of the movable table (cutter holder); 7—lead screw M12; 8—left screed, right not conventionally shown (screw M12.2 pcs.); 9—flywheel with a handle; 10—cotter pin d3; 11 — overlay (steel sheet s3); 12—fixing the lining to the body (M4 screw, 2 pcs.)

Preliminary supply of workpieces to the cutting tool can be carried out "manually", by loosening the screws that fasten its body to the base table, and moving the entire support in the grooves (oblong holes).

The movement of the platform is carried out from the handle-flywheel by a lead screw with a regular M12 thread. There is no matrix nut as such in the mechanism. A corresponding threaded hole, together with a pair of pilot holes, is made in the cross member under the platform. The guides themselves are a pair of standard long M12 screws. I must say that the support table can be moved up to 60 mm, although for cutting grooves and slots, as a rule, more than 10 mm is not required.

As noted earlier, the depth of cut (feed) when working on the machine is small. To speed up the production of “GOST” keyways, you can use the technology for drilling semicircular “collective farm” grooves given at the beginning of the article, and then refine them to a rectangular section using a slotting machine.

G.SPIRYAKOV. Chelyabinsk

Keyways (grooves) on the shafts are made for parallel and segmental keys. Keyways for feather keys can be closed on both sides (blind), closed on one side and through.

Keyways are made in a variety of ways depending on the configuration of the keyway and shaft and the tool used. They are performed on horizontal milling or vertical milling machines for general purposes or on special machines.

Keyways through and open on one side are made by milling with disk cutters (Fig. 22, a).

Rice. 22. Methods for milling shaft keyways: a– disk cutter with longitudinal feed; b– end mill with longitudinal feed; in– end mill with pendulum feed; G– disk cutter with vertical feed

Groove milling is carried out in one or two passes. This method is the most productive and provides sufficient accuracy of the groove width, but its application is limited by the configuration of the grooves: closed grooves with rounded ends cannot be made in this way. Such grooves are made by end mills with longitudinal feed in one or more passes (Fig. 22, b).

Milling with an end mill in one pass is performed in such a way that at first the cutter at vertical feed passes to the full depth of the groove, then the longitudinal feed is turned on, with which the keyway is milled to its full length. This method requires a powerful machine, a strong attachment of the cutter and abundant cooling with an emulsion. Due to the fact that the cutter works mainly with the peripheral part, the diameter of which decreases from regrinding to regrinding, as the number of regrindings increases, the machining accuracy (along the groove width) deteriorates.

To obtain the exact width of the grooves, special keyway milling machines with “pendulum feed” are used, working as double-spiral end cutters with frontal cutting edges. With this method, the cutter cuts to a depth of 0.1–0.3 mm and mills the groove to the full length, then cuts again to the same depth as in the previous case and mills the groove to the full length, but in the opposite direction (Fig. 22, in). This is where the name "pendulum feed" comes from.

This method is the most rational for the manufacture of keyways in serial and mass production, since the accuracy of the manufacture of the groove ensures interchangeability in the keyway. In addition, since the cutter works with the frontal part, it will be more durable, as the frontal part of the cutter wears out, and not the peripheral part of the cutter. The disadvantage of this method is the low productivity. From this it follows that the pendulum feed method should be used in the manufacture of grooves that require interchangeability, and the single pass milling method should be used in cases where it is possible to fit the keys to the groove.

Keyways for segmented keys are made by milling using disk cutters (Fig. 22, G). Through-keyway shafts can be processed on planers (long grooves on planers and short grooves on cross planers).

Keyways in the holes of the bushings of gears, pulleys and other parts that are put on a shaft with a key are processed in individual and small-scale production on slotting machines, in large-scale and mass production - on broaching machines.

Typically, a lathe is used for boring, threading, reaming, countersinking and drilling, but their capabilities do not end there. I propose to consider a way to use it to hollow out the keyway on the bushing. To do this, I use a 1K62 screw-cutting lathe.

Set of tools

To perform the work, in addition to the machine, you will need:

• boring cutter;
• slotting cutter;
• oil for lubrication.

Any boring tool can be used, of course, within the limits of the sleeve diameter. As for the slotting tool, its cross section is selected for the required width of the keyway. Lubricating oil is required only when working with hard metal. For mild steels, provided that high-quality cutters are used, it is not necessary, since chamfer boring and slotting does not cause critical overheating, which can accelerate the erasure of the cutting edge of the tool.

Preparatory stage

The bushing is installed in a three-jaw chuck. Before chiselling, you must first prepare its inner and outer chamfer with a boring tool. They are made only from the side from which the slotting tool will enter. This is the simplest process familiar even to an amateur turner, therefore it does not require separate consideration.

After preparing the chamfers on the machine, you need to set the minimum speed to prevent the spindle from scrolling. On many machines, the chuck can give backlash under load, so in this case it is necessary to put a spacer. To do this, a bolt with a nut of a suitable height is placed under it. When it is unscrewed, the length of the stop increases, so it is pressed tightly against the cartridge, thereby removing the rolling.

The grooving tool is slightly clamped in the tool holder. He sets the bushings in the center, after which it is necessary to make fine adjustments. To do this, it is inserted into the sleeve, moving longitudinally with the caliper along the sled. The resulting scratch should run along the sleeve bore from one edge to the other. In the cut line, there should not be an area without a scratch. If it is, then this is to talk about the presence of a bias. When the cutter is set correctly, it must be clamped very tightly, as the load during chiselling is much higher than when performing standard turning work.

Chiselling process

Since the bushing has its own radius inside, before starting to measure the depth of the groove, it is necessary to cut it off in order to get a flat area, which will be the zero reference point. To do this, with the help of a caliper, I move the cutter inside the sleeve along the longitudinal slide, removing the thinnest metal shavings. After it returns to its original position, I bring the cutting edge closer along the transverse slide to the body of the sleeve by 0.1 mm. Again I make a longitudinal movement along the carriage. I repeat the process until the gutter loses its radius. As soon as he leaves, this will be the zero point for reference.

Now I start chiseling the keyway. In my case, its depth should be 2.6 mm. Using 0.1 mm increments, it would take 26 cutter movements to reach this depth.

After deepening the groove by 2.6 mm, without changing the setting on the limb, make a few more repeated movements of the cutter to clean the plane from small burrs. Next, the sleeve is removed from the cartridge. Her second end is rather rough, but this is easily solved. The boring tool is again installed in the tool holder, and accurate chamfers are removed. After that, the sleeve can be used for its intended purpose.

Chiselling on a lathe is a lengthy, though not complicated process. In my case, the longitudinal movement of the caliper is motorized, so everything is done relatively quickly. It is also possible to gouge a groove on budget hand-operated machines, but in this case it will take much more time.