How to drill screw inserts in D.I.Y. table?

[timothyleong]

Hi there, I am assembling a DIY table and want to make sure that Im on the right track. The table legs came with M6 bolts and I bought these screw inserts (link below). What drill bit sets do you recommend for the job? And what size hole should I be drilling the inserts?

I plan on using an allen key to screw the inserts in so I may not need an impact driver.

Any feedback would be appreciated. Thanks!

https://www.bunnings.com.au/taskmaster-m6-x-13mm-screw-in-insert-nut-flat-surfaces-8-pack_p0035526

[TedBear]

Hi @timothyleong 

That sounds like an interesting project... hopefully we will get to see the finished product here on Bunnings Workshop.

I haven't used those particular Inserts, but there should be a drill size guide on the pack - and the feedback below the product page from users who have used them suggests that they can be fragile, so a cautious approach is needed.

The size of the hole can vary slightly - depending on the softness\/hardness of the timber being used.

Generally, you measure the outside of the Insert's barrel - that is imagine that the threads have been removed.

If your timber is relatively soft, use that as the hole the hole size so that the max amount if thread bites in. If the timber is hardwood, add another 0.5mm so that you are not straining the insert itself when inserting.   

You can "measure" by eye -  hold up a drill bit behind the Insert to get a good idea of whether it will clear a hole for the Insert's body while also leaving enough timber to grip the thread.  

To insert it, especially given the reports of fragility, I don't recommend using the hex driver.

A better way that protects the Insert is to get a bolt of the size that screws into the insert (6mm) and a nut and washer to suit.

Screw the nut part way up the bolt, followed by the washer, and then insert that into the insert such that it occupies all the insert's thread.

Then tighten the nut onto it (finger tight should do).

Now use that to drive in the Insert, tightening via the bolt head. This will ensure that you get it to the correct depth (ie flush with the top) while also protecting the body of the Insert from sheering forces (as would be the case when all the force comes only from the top of the Insert) as it goes in.

Make sure you keep it square as you go, which is easier to see using the bolt and nut method.

You can use a power driver, since this method prevents over shooting the depth (the washer stops it at the correct depth).

I hope that helps.

[MitchellMc]

Hi @timothyleong,

That's some brilliant advice @TedBear has provided. Start with a 5.5mm drill bit if this is Pine, and you might need to go up to 6.0mm if you encounter resistance. Please do not use an impact driver on these inserts, as they will most likely break.

Let us know how you go.

Mitchell

[timothyleong]

Hi guys,

Thanks for the helpful and really detailed responses.

I forgot to mention that the table is a walnut rubberwood desk. So im guessing 6.omm bit would be better?

My screws are 15mm and the table is 25mm , do I need to drill 15mm into the wood as well?

And also would this drill be enough for the job? https://www.bunnings.com.au/ozito-pxc-18v-cordless-multi-chuck-drill-kit_p0370064

I will definitely try to post photos when im done!

[EricL]

Hello @timothyleong

The screw inserts are 13mm deep, drilling 15mm deep means that the inserts will sit further into the table. If you want the inserts to finish flush with the table, I suggest drilling only 13mm deep and testing one of the inserts. If the insert does not sit deep enough add 1 millimetre to make the drill hole 14mm deep.

The drill you've chosen is good, if you're planning on doing more D.I.Y projects it's an excellent one to start with. 

Please keep us updated with your progress, we look forward to seeing your table assembled and ready for use.

If you need further assistance, please let us know.

Eric

[TedBear]

Hi @timothyleong, further to EricL's advice, if you need further depth to accommodate the length of the screws then drill the hole for the insert first at the correct depth for the Insert, then use a thinner bit that is correct for the screw to add depth for the screw. That way the insert should go down to the right depth, while the screw tip can continue further if necessary.  Use a depth stop on the bit so you don't go too far.   If you don't have one, use a piece of tape wrapped firmly to the bit,  with a piece sticking out to the side (like a small flag) to let you know when you're there. (When the dust gets cleaned off the work by the flag. )

[timothyleong]

Hi there, just an update so far. I drilled the hole on the right with a size 6 drill bit. It felt abit too small for the insert. I then used a size 8 drill bit the drill the hole on the left. I managed to screw the insert abit but now im stuck. Do you have any suggestions how to push in the insert more? And is the size 8 drill just right or too small? Thanks for your help and patience so far!

[MitchellMc]

The 8mm is looking about right @timothyleong, and you couldn't go much larger before the thread doesn't grip anymore. The idea is that the thread cuts into your timber, so there will be resistance when it starts to cut. When you say you're stuck, what's happening? Is it just getting stiff to screw, or has it stopped no matter what amount of force you put on it?

Is that an insert you've managed to get in further down the table?

Mitchell

[Noyade]

Hello @timothyleong 

I used something similar - TaskMaster Code 12243 - 6 X 20mm. But for the life of me I can't remember what the project was.

My external examination revealed they are slightly tapered and if you disregard the outer wood-biting thread diameter, the tubular body is 8.3 mm in diameter at the top and 7.5 mm at the bottom. Mine don't have the flange at the top.

They are of a brittle aluminium construction. I'll type that word again "brittle."

From memory I had to practise on spare wood with various drill sizes and I think in the end I used a lubricant to assist with the 'insertion.'

And that was for softwood.

It's very easy with a 6mm allen key to shatter the top section, and if you do that they can be hard to remove.

Go slow.

Not a product I'm in a hurry to use again.

Best of luck to you.

[timothyleong]

Hi @MitchellMc so the insert is quite stiff to screw and dosen't move anymore. I feel that it would screw in more if alot more force was added but am afraid to break the insert. 

I only tried using a screw driver and allen key at the moment. Im probably going to get a socket wrench and try the bolt/washer and try to screw it in somemore.

I also thought of getting an impact driver but would that be too much to break the insert do you think?

Yeah the insert further up was done by the manufacturer... But im using different legs thats why had to screw in my own.

Thanks @Noyade, yeah everyone stressed that it was brittle too. Do you remember what lubricant you used or what sort do you recommend?

Or do you recommend other inserts? And where I could get them?

Thanks again guys!