Bench drill guidance - holding sheet and strip material

[Mark Forrest]

All the gear, no idea....

A few years ago I treated myself to a lovely little Proxxon TBM220 bench drill which I have found to be a very useful addition to my modelling tools.

 

However, I found that the machine vice provided wasn't that helpful when it comes to drilling holes at regular intervals in sheet or strip material.

More recently, I've added a KT70 compound table to the TBM220, which helps greatly with accurate spacing between holes.  What I'm not sure about is the correct way to securely hold/clamp thin sheet or strip material to the table.

I have been attaching ply or MDF to the compound table, than using double sided tape to fix brass or plasticard strip/sheet to this.  Is that the correct way or is there something that I'm missing?

[polybear]

Seems fine to me - there are various ways of doing it.  So long as the method you use

(a) holds the work securely, without risk of injury

(b) doesn't damage the work

(c) avoids risk of damage to the bench drill

- then it's fine in my book

[Daddyman]

I have the same set up - and started out with the same problem, and the same solution, supergluing the workpiece to the wood. That was OK for metal parts. However, a better solution is to clamp the bench vice to the coordinate table - it's designed to be used that way with all bolts and spacings matching.   

[Daddyman]

Also, get yourself some centre drills. You'll find that normal drills will waggle about in the chuck too much to give you a good round hole. Try, for example, Drill Service. I have "CD-0.5X3.15R 0.5x3.15 HSS Centre Drill Radius Type SE" and recently bought a 0.4mm centre drill - perfect for doing buffer beam bolt holes on the coordinate table.

 

Note that engineers will call centre drills something else (can't remember the term, sorry), but "centre drill" seems to get you what you need with retailers - well, certainly with Drill Service. 

[Daddyman]

Also, the advice I was given was that you need some sort of reminder to yourself to take out the chuck key before turning the drill on - masking tape round the key, close peg on your nose, etc. If you turn it on at 15,000 (?) rpm, it doesn't bear thinking about what the flying key could embed itself in. 

Edited October 5, 2023 by Daddyman

[JeffP]

Depending on where the holes are in the sheet metal, using a couple of self tapping screws into the ply/mdf, with large, (repair) washers, works well.

[Jeremy Cumberland]

I always clamp sheet metal, having once had a piece pick up as the drill bit broke through. Your clamps will be fine for this, just put a piece of scrap wood underneath the metal sheet.

 

If you use the machine vice, you'll probably use this to clamp the wood, and then use separate clamps to hold the sheet onto the wood. I use toolmakers clamps, but G-clamps or hand vices will work just as well. The main concern is finding something that doesn't get in the way of the drill.

 

Whether the sheet is likely to pick up or not depends on the sheet thickness and drill diameter, and whether the sheet is likely to injure you depends on the sheet thickness and what the edges are like. If you're only drilling 1 mm holes, for example, then taping the sheet down might well be fine. For 3 mm holes, I'd definitely clamp.

[Jeremy Cumberland]

3 hours ago, Daddyman said:

Also, the advice I was given was that you need some sort of reminder to yourself to take out the chuck key before turning the drill on - masking take round the key, close peg on your nose, etc. If you turn it on at 15,000 (?) rpm, it doesn't bear thinking about what the flying key could embed itself in. 

I'd recommend getting used to never, ever, letting the chuck key out of your hand while the key is in the chuck. All the time you are securing the chuck, whatever the machine, keep hold of that chuck key. If you need two hands to do some adjustment while you are tightening the chuck (unlikely with a drill, but fairly common with a lathe), put the chuck key down somewhere safe.

[Jol Wilkinson]

3 hours ago, Daddyman said:

Also, get yourself some centre drills. You'll find that normal drills will waggle about in the chuck too much to give you a good round hole. Try, for example, Drill Service. I have "CD-0.5X3.15R 0.5x3.15 HSS Centre Drill Radius Type SE" and recently bought a 0.4mm centre drill - perfect for doing buffer beam bolt holes on the coordinate table.

 

Note that engineers will call centre drills something else (can't remember the term, sorry), but "centre drill" seems to get you what you need with retailers - well, certainly with Drill Service. 

A great tip. Here is another source of small centre drills.

 

https://www.rdgtools.co.uk/acatalog/Centre-Drills-Metric-Sizes.html

 

I have found that good quality "large shank" drills also work well. I use Busch, available from Cooksongold 

 

www.cooksongold.com

[Daddyman]

I found the product number for the 0.4mm centre drill - it came from Associated Production Tools.

The photo also shows the bufferbeam I drilled out with it, with the workpiece clamped in the machine vice, clamped in turn to the coordinate table. (Once drilled, all the holes were plugged with 0.4 wire and filed to length.) 

[Mark Forrest]

13 hours ago, Daddyman said:

I have the same set up - and started out with the same problem, and the same solution, supergluing the workpiece to the wood. That was OK for metal parts. However, a better solution is to clamp the bench vice to the coordinate table - it's designed to be used that way with all bolts and spacings matching.   

Thanks, I (now) see how the vice attaches to the table, I'd missed that.  I can see how that would be useful when drilling section or tube. 

Presumably with strip or sheet material you still need to fix that to a piece of wood that is then held in the vice?

[Daddyman]

10 hours ago, Mark Forrest said:

Thanks, I (now) see how the vice attaches to the table, I'd missed that.  I can see how that would be useful when drilling section or tube. 

Presumably with strip or sheet material you still need to fix that to a piece of wood that is then held in the vice?

You could so I suppose, but I wanted to get away from that, which is why I bought the vice to go on top of the coordinate table. With the b.beam I think I just held it in the vice jaws, not wood. It has to be tight enough not to move, but not so tight that it's distorting the workpiece (the b.beam was 10 thou). You've always got the option of using an oversize piece of metal, and then trimming down to your component afterwards.  

[Jeremy Cumberland]

It depends on what you're drilling. The workpeice mustn't move under the drill (think how much downwards force you are applying). Usually for strip and sheet, this means supporting it on wood, with the wood either clamped so it can't move or else resting on something solid, such as the table or the bottom of the vice.

 

If the workpiece is stiff enough so it won't bend, and has edges that the vice will grip, then you can hold it in the vice, but I'd still put it on top of a piece of wood, the wood being narrower than the strip so the vice grips the workpiece rather than the wood. Vices are good at stopping things from moving sideways, but if there's not much edge to grip on, they aren't always good at stopping things moving downwards.

 

For sheet, or anything that can't be held directly in the vice, use the vice to hold a piece of wood and secure the workpiece on top. It doesn't matter whether you fix the workpiece to the wood before you put it in the vice, or whether you clamp the wood first then secure the workpiece to it. Make sure that all the holes you want to drill are where the wood is, and it doesn't matter if other parts of the sheet overhang,

[Daddyman]

3 minutes ago, Jeremy Cumberland said:

It depends on what you're drilling. The workpeice mustn't move under the drill (think how much downwards force you are applying). Usually for strip and sheet, this means supporting it on wood, with the wood either clamped so it can't move or else resting on something solid, such as the table or the bottom of the vice.

 

If the workpiece is stiff enough so it won't bend, and has edges that the vice will grip, then you can hold it in the vice, but I'd still put it on top of a piece of wood, the wood being narrower than the strip so the vice grips the workpiece rather than the wood. Vices are good at stopping things from moving sideways, but if there's not much edge to grip on, they aren't always good at stopping things moving downwards.

 

For sheet, or anything that can't be held directly in the vice, use the vice to hold a piece of wood and secure the workpiece on top. It doesn't matter whether you fix the workpiece to the wood before you put it in the vice, or whether you clamp the wood first then secure the workpiece to it. Make sure that all the holes you want to drill are where the wood is, and it doesn't matter if other parts of the sheet overhang,

Good advice. I think I just got away with it without the wood because my work piece was so narrow, so proportionally stiffer than you'd expect from 10 thou. But I wouldn't like to do it without wood for a larger piece.  

[JeffP]

A wooden "drilling table" from mdf, ply etc is useful.

Glue and screw a piece of 25 mm square timber with planed and square edges across the centre of one side.

This can then be the bit held in the drilling vice.