Question

steps to drill, boring and reaming for 30 mm diameter of workpiece

Answer 1

Given a workpiece of 30 mm diameter. Lets assume we have to obtain a final hole size of 10mm ⁺_{-0.10 mm} tolerance, The hole is through hole, ie

Steps for drilling:

1. Surface preparation: The workpiece is nicely cleaned of any rust or any other foreign material from the surface. The location for the required hole is identified and a centre punch is punched on the centre of the hole. The workpiece is held strongly on the vice of the drilling machine.

2. Wood is placed below the workpiece so that the through hole drilling will end in the wood so that drill bit will not come in contact with the vice.

3. A 8mm standard drill bit is selected and is fitted on the chuck. 8mm is used instead of directly using 10mm because drilling a larger hole is more difficult and can lead to overloading of the drill bit leading to failure. Also we can carry out boring using a 10mm boring tool later to obtain the desired hole dia.

4. Drilling machine is switched ON, and a small spot drill is carried out just to see that the drill is passing through the punched hole.

5. Deep hole drilling is carried out at a slow and steady rate. Occasional cooling of the drill bit can be carried out so that drill bit do not overheat and damage or break in the process.

6. Ensure that chips move out positively from the drilled hole.

7. Whe the through hole is drilled, the drill bit touches the wood and as wood starts to get drilled, we can lift up the drilling tool and switch OFF the drilling machine.

Steps for boring:

1. Here also steps are similar except that a 10mm boring tool which is supported at both the ends is used and boring of the hole to 10mm dia hole is carried out.

2. Boring is carried out at a dia of 10mm.

3. After boring also, few burrs will be present in the hole due to material removal, and this can be removed using reaming tool.

Steps for reaming:

1. Reaming tool is used to increase the surface finish of the drilled hole.

2. Use a reaming bit of 10mm +/- of 0.05mm tolerance. This will ensure that drilled hole is within the tolerance limit.

3. Reaming is carried out on the remaining hole and desired surface finish is obtained