Preliminary Requirements

Safety Requirements

WARNING

IT IS THE RESPONSIBILITY OF THE OPERATOR TO OBTAIN AND OBSERVE THE MANUFACTURERS MATERIAL SAFETY DATA SHEETS FOR CONSUMABLE MATERIALS INFORMATION SUCH AS, HAZARDOUS INGREDIENTS, PHYSICAL/CHEMICAL CHARACTERISTICS, FIRE, EXPLOSION, REACTIVITY, HEALTH HAZARD DATA, PRECAUTIONS FOR SAFE HANDLING, USE AND CONTROL MEASURES AND ALSO TO TAKE LOCAL REGULATIONS INTO CONSIDERATION.

Procedure

1. SUBTASK 70-32-01-320-001 Taper Bolts

   1. Two special types of taper bolts are used.

      1. NOTE

         These bolts are only supplied in a range of oversizes.

         Case hardened and centerless ground bolts.

      2. NOTE

         These bolts can be supplied in a range of oversizes. Alternatively, they can be supplied as a maximum oversize bolt which can then be ground to the reamed hole dimensions.

         None case hardened bolts with grinding centers.

   2. The usual type of external grinding machine, with an offset bed to make the necessary taper, can be used; to grind the maximum oversize bolts to the necessary taper. Examine the offset of the machine with a taper setting mandrel. The mandrel will also be used to offset the machine to grind the reamers again.

   3. The dimensions to which each bolt must be machined, is controlled by the tapered hole; which must be correct and with the necessary draw. Also, the angle of the taper must be examined with a taper bolt gage. A zero indication must be available when the bolt is installed in the gage to examine the taper.

2. SUBTASK 70-32-01-320-002 Reaming

   1. Two types of reamer are used.

      1. The four-lip parallel reamer: This is only used when new parts are to be installed. This makes sure that the position of the hole is accurate and gives a guide hole for the taper reamers to follow.

      2. The taper reamer: This is used to ream and finish the taper holes. A stop on the reamer controls the depth of cut and the dimensions of the tapered hole. The stop must be set for the quantity of metal to be removed. A range of oversize reamers is available.

   2. Preparation.

      1. Clean all the parts, the fixtures and the bolts, with dry compressed air and solvent , refer to the SPM TASK 70-11-26-300-503 to remove all dust and other unwanted material.

      2. Install and attach the fixture base to the work table or base plate of the radial arm drilling machine.

      3. Use a 0.0015in. (0.038 mm) thick feeler gage to do a bedding check between the fixture base and the machine table, at different points around the edge. If necessary, use some packing to attach the clamps.

      4. Install the assembly on to the fixture base in a position approximately related to the machine.

      5. Use a dial test indicator (D.T.I.) to make sure that the datum face of the assembly is parallel with the machine. Apply some packing if necessary.

      6. Attach the assembly to the fixture.

      7. 

         CAUTION

         MAKE SURE THAT ALL THE OFFSET HOLES IN THE ASSEMBLY AND BUSH PLATE ARE CORRECTLY ALIGNED.

         Assemble the reaming bush plate to the assembly with the jig location and fouling pins.

      8. Make sure, with the D.T.I. attached to the machine spindle, that the reaming bush top faces are at 90 degrees to the machine spindle. If necessary, correct with some packing applied to the reaming fixture base.

   3. Set and examine the new reamers and those that were ground again.

      1. Examine the reamers before they are used for signs of damage and corrosion to keep the possibility of score marks to a minimum.

      2. If it is necessary to increase the spindle length with an extension socket, examine the reamer visually. Make sure that it is correctly aligned and concentric when the spindle is turned at the necessary speed.

      3. NOTE

         The reamer is adjusted with two wrench bars which are used on the knurled adjuster nuts of the reamer holder.

         Adjust the cutting depth of the reamer with the correct setting gage.

         1. Adjust the reamer until the setting gage touches the mating face of the top knurled nut; when it is set at the reamer cutting diameter.

         2. Lock the nuts.

         3. Examine the reamer when the setting gage is locked and again during the reaming procedure; if more than one hole is to be reamed.

   4. Parallel reaming.

      1. Install the correct parallel reamer into the drilling machine spindle.

      2. NOTE

         If the reamer is not correctly set, it will rub against the internal wall of the guide bush. This can only be felt with practice. To correct the defect, loosen the spindle head and set the reamer again. If this procedure does not correct the defect, examine the position of the bush plate again.

         Set the spindle speed to between 80 and 150 rpm, as specified for the hole diameter and material to be reamed.

      3. Set the vertical feed to approximately 0.010in. (0.25 mm) from each turn of the spindle.

      4. Open the valve to control the flow of CoMat 10-001 CUTTING OIL.

      5. Start the spindle drive and the vertical feed of the machine. Parallel ream the hole until it is 0.075 in. (1.91 mm) from the set stop on the reamer shank.

      6. Stop the vertical feed, then feed the remaining cutting procedure by hand.

      7. Remove the reamer from the drilling machine.

   5. Rough taper reaming.

      1. Install the rough taper reamer into the drilling machine spindle.

      2. NOTE

         To make sure of a good quality finish, always use CoMat 10-001 CUTTING OIL. Frequently remove the reamer from the hole, to apply the oil.

         Use a spindle speed of approximately 45 rpm to hand feed the reamer in steps of 0.025 in. (0.64 mm). Lift the tool between each step to help remove the unwanted material from the hole.

      3. Lift the reamer, when the reamer shank stop is 0.025 in. (0.64 mm) from the guide bush top face.

      4. Clean the reamed hole with a bottle brush that is soaked in solvent , refer to the SPM TASK 70-11-26-300-503.

      5. Examine the inner surface of the hole. If the hole is satisfactory, assemble the bush plate and continue with the rough taper reaming.

   6. Finish taper reaming.

      1. Install the finish taper reamer into the drilling machine spindle.

      2. Use CoMat 10-001 CUTTING OIL, then hand feed the reamer into the hole until the cutting starts.

      3. Feed the reamer 0.025 in. (0.64 mm) more into the hole.

      4. NOTE

         Do this check with a feeler gage below the reamer stop.

         Lift the reamer, stop the spindle movement, then remove the bush plate. Clean and examine the hole, as specified in steps E.(2) to E.(4).

      5. Do Step again, until the reamer is 0.015 in. (0.38 mm) vertically above the stop.

      6. Remove the reamer from the drilling machine.

      7. Turn the reamer by hand and examine the bolt draw in the hole. Use a bolt of the correct dimensions, as specified in Step.

      8. NOTE

         Step permits the correction of small defects that do not cause oversize holes to be made.

         Do Step again until you get the maximum permitted bolt draw.

      9. Ream the remaining open holes in the assembly. If necessary, set the adjustable stop on the taper reamer shank again.

      10. Examine the surface finish and the hole dimensions, as specified in the related Repair Scheme.

   7. NOTE

      The procedures that follow are for the split-taper reaming of two components together; when one component is made of "softer" material and the other component is made of "harder" material. Refer to General.

      Split-taper reaming.

      1. Parallel ream and rough taper ream the assembly, as specified in steps D. and E.

      2. NOTE

         Do this check with a feeler gage.

         With the two parts assembled, finish taper ream the holes until the reamer stop is 0.015 in. (0.38 mm) vertically above the bush plate.

      3. Remove the bush plate and disassemble the two parts when all the slave bolts are removed.

      4. Use a taper bolt of the correct dimensions.

         NOTE

         When reaming the lower part use a distance piece, of the correct dimensions, to make an allowance for the upper part.

         All differences in the upper part must be corrected, as an increase or decrease of the draw when necessary.

      5. Hand ream the hole in the "softer" of the two materials, to give the correct draw between the bolt head and the component (Refer to Step).

      6. Slowly and continuously machine ream the agreed hole in the "harder" material, as specified in step F. Make sure you get the same draw, 0.002 in. (0.05 mm) with the same bolt, as that between the bolt and the "softer" part (Refer to Step).

3. SUBTASK 70-32-01-320-003 Examine the Bolt Draw

   1. To get the specified conditions, taper bolt holes must always be reamed to give the correct bolt draw. This is the distance between the mating face of the bolt head and the assembly (Refer to Figure).

   2. Each bolt must be installed in its related hole when the correct bolt draw is found.

   3. The necessary bolt draw and the procedure to be used will be specified in the related Repair Scheme.

   4. The procedure to examine the bolt draw is as follows.

      1. Clean the hole with a brush soaked in solvent , refer to the SPM TASK 70-11-26-300-503 and compressed air.

      2. NOTE

         Apply light hand pressure only.

         Install the correct bolt in the tapered hole and push it fully in.

      3. Examine the bolt draw with a wedge or a feeler gage.

4. SUBTASK 70-32-01-320-004 Defects

   1. NOTE

      With light scores it is not necessary to remove more than 0.002 in. (0.05 mm) of metal from the diameter, to repair a hole.

      Light scores.

      1. First set the reamer shank stop to get the correct cutting depth.

      2. Ream the hole at this adjustment.

      3. Examine the hole with a blueing gage (Refer to General).

      4. NOTE

         It is not necessary for all the holes to be of the same dimensions. If the holes are not damaged, they must not be reamed.

         If the hole is satisfactory, ream the remaining damaged holes at the same adjustment.

      5. If more reaming is necessary, adjust the reamer cutting depth again. Alternatively, use the correct oversize reamer and do Step and Step again.

   2. NOTE

      Reaming to a larger diameter must not be done to remove the fluting because the condition can become worse.

      Fluting.

      1. If fluting occurs in a hole, it must be removed with a tapered lap tool and a fine grade lapping paste.

         .

Figure: Examine the bolt draw

Examine the bolt draw