Drill capable do go through 5 oak sleepers stacked

Discussion in 'Tool Talk' started by LiviuM, Jul 9, 2021.

  1. LiviuM

    LiviuM New Member

    Hello community,

    This is my first post here and I would really appreciate some help.

    I'm building a retaining wall, 6 rows high. The sleepers are stacked on their wide side. I managed to stack 5 rows quite nicely and now, before putting the last row, I want to insert some oak dowels going all the way from top to bottom to make everything solid.

    I've started with a Bosch AdvancedImpact 900. This drill was quite capable with drilling pilot holes and screwing 150 mm stainless steel screws. But when it came to drilling with a 25mm x 600mm auger bit, it only managed go through 1.5 rows before smoke came out of it. A very feisty drill. It didn't died. But 900W input power and the torque it could provide weren't enough.

    Then I went for a Titan TTB631SDS only to find out I cannot use it in reverse so I gave it back.
    Then I went for a Bosch GSB 21-2 RE thinking 9 times more torque than the first Bosch, and 1100W input power will do the trick. It didn't. It managed to go through some 3 - 3.5 rows and got jammed. To be honest, I was really disappointed with this tool. Currently, this drill it's three times more expensive than the AdvancedImpact 900 but the price difference didn't make much difference when it came to actually used it.

    So the question is, is there a drill capable to go through 5 rows of oak sleepers with a 25mm x 600mm auger bit? And of course, to not have to break a bank to buy it.

    Thanks a lot people. I'm really looking forward for any advice with this.
  2. CraigMcK

    CraigMcK Screwfix Select

    Are you pecking at the hole and retracting the drill every so often to remove the cuttings?

    Is the auger still sharp?
  3. LiviuM

    LiviuM New Member

    Hi Craig. I tried drilling the hole without retracting because the more I do that, the more the hole will widen. I've notice this when drilling the pilot holes. My understanding about these auger bits is that they are designed to pull out the wood cuttings/debris. And it did. As long as the drill bit went in, a lot of wood pieces came out.

    The auger bit is made by Sealey and it feels very sharp. Now it's stuck in the wood. I've put some chainsaw oil around it (the only one I could find in my shed) and I'll try to extract it tomorrow using a spanner (the bit has hexagonal head).
  4. Kas228

    Kas228 Screwfix Select

    As an alternative could you not fix a suitable length of steel plate down the back side (presuming it’s not on show) of the sleepers, spaced along the length at suitable distances. This would achieve the same would it not and be a lot less aggro.
    Or in hindsight attached them as your going along offset would have achieved the same.
    rogerk101 likes this.
  5. AndBlue

    AndBlue Member

    I would have attached the problem in a more practical and achievable way. Big dowels jointing row1- row 2, then row2-3 and so forth. The rows are all joined. A couple of joist hangers down the back lining all rows will add a secondary fix.
    Having found you can drill through 3-5 rows, why not re-stack and joint your 1st three rows, then when you add row 4, its jointed for rows 2,3&4, then row 5 jointed to rows 3,4&5.
    Perhaps my biggest query is how you will achieve lateral stability. You now have lumps of wood 20" high, presumably you will lean something against it. What will you do to stop the 20" wall falling over? IMHO, the 8" wide base won't be enough. Just a thought
    I-Man likes this.
  6. Jim Kirk

    Jim Kirk Member

    The original drills for sleeper augers on the railways were petrol friven mainly due to location and lack of power and that was just for one sleeper. I cannot even imagine what sort of power would be required for a 600mm auger and what sort of drive it would need, but it would be horrendously expensive if there was one - something like a pole/post auger.
    This sort of thing is usually done with steel rope and staples down the front of the sleepers and taken over the top and staked back to supoort the whole wall.
  7. LiviuM

    LiviuM New Member

    Thank you all for your responses. Very much appreciated.

    @AndBlue You're right and that was my first thought before finding an auger bit that long. I was planning to drill an oak dowel through 3 sleepers at a time. Something like 1-3, 2-4 and 3-5. But then I found there is actually an auger bit to allow me to go through all of them at once. That was before learning in the hard way that it's not easy to actually do that.
    The sleepers are laid down on their wide side (200mm) and are currently stuck in place with 150mm stainless steel screws. The whole thing is pretty rock solid, but this can change rapidly once I start backfilling with soil.

    @Kas228 Your suggestion seems reasonable and judging by how things look, I'm thinking to combine the metal plates with some metal rods/posts/whatever behind the wall (stuck in concrete). I'm not a big fan of posts behind the wall and I tried as much as I could to avoid doing this (due to some tree roots I have there), but it seems I have no choice. But before that, once I get the auger bit out, I will try one more time but this time taking in consideration what Craig said (retracting every 100-150mm).

    Before going for Bosch 21-2 RE, I was really tempted to go for Bosch GSB 162-2 RE. I'm glad I didn't as the difference between them doesn't seem too big once they encounter some real challenge. They might be goood for softwood and even concrete, but for hardwood, not a chance. And GSB 162-2 RE it's a £400 product, even more than that on many websites. 21-2 RE was close to £200.
  8. AndBlue

    AndBlue Member

    @LiviuM you may want to look at how you will stop the sol pushing the stack over. Your dowels / interlock will only secure the sleepers with no lateral support. Coupl of big spikes in the ground then attach galvanised roof straps to the sleepers will help that sideward movement.
  9. LiviuM

    LiviuM New Member

    @AndBlue I'm counting on the fact that there are some angles in the wall and there isn't much soil going in the back of the wall.

    fg.jpg fg2.jpg
  10. Kas228

    Kas228 Screwfix Select

    Looking good, as it’s not a straight line (which for some reason I thought it would be) you have more strength.
    What’s the total weight of all that timber, any chance of forward movement once the earth is placed up against it?
  11. LiviuM

    LiviuM New Member

    @Kas228 I was pretty curious as well about the weight so I weighed myself with and without a sleeper in my arms. These things are more or less 50-55Kg each. So there are roughly 125-130Kg pushing downwards for every 1m of wall. But because they are interlocked, the weight is probably even more than that. I haven't measured the length to be honest, but the whole thing is easily 1 ton of wood. But the soil behind will be easily 3 tons judging by how much I dug out.
  12. Kas228

    Kas228 Screwfix Select

    In that case I cant see it going anywhere. If it is a concern you could always put an anchor of some sort into the ground at either end (and centre) maybe.
  13. FlyByNight

    FlyByNight Screwfix Select

    If you do finally manage to drill through all five, then maybe think about a steel rod hammered down into the soil below and 50mm below teh finished surface, then a wooden plug.
  14. LiviuM

    LiviuM New Member

    Good news. I managed to pull the drill bit out and to drill through all five sleepers. The solution was to retract the drill bit every now and then. Every 1-2 cm of wood drilled will fill 3-4 twists of the bit. So my expectations for the drill were clearly disproportionate. The problem with these auger bits is that once they bite the wood, they will want to go deeper and deeper very fast so it's very important you don't let it do that and retract immediately once the drill starts struggling. It's not an easy task, clearly.
  15. FlyByNight

    FlyByNight Screwfix Select

    Even when drilling a softwood 50mm joist, I find it essential to reverse the drill after about 3-4 cm. With a decent auger you will not find it enlarges the hole diameter due to where it cuts.

    What glue are you using for teh dowels? I would suggest Gorilla original expanding https://www.screwfix.com/p/gorilla-glue-250ml/51887
  16. LiviuM

    LiviuM New Member

    I managed to push in my first dowel. It wasn't easy. But drilling the second hole it's a nightmare. The oak is simply destroying my auger bit. I need to order another one and Sealey clearly will not be on my shopping basket again.

    Any idea if predrilling with a smaller bit would help? I'm thinking to use a 12mm or 16mm bit before going with the 25mm one.
  17. Jord86

    Jord86 Screwfix Select

    Yes it would vastly help, you will be there all year doing it the way you have described. Look on Axminster tools site and get yourself a couple of Fisch Forstner bits, they aren't cheap but are some of the best.
  18. Mr Rusty

    Mr Rusty Screwfix Select

    Looks good. I think if I'd made that I would have used stainless M10 or M12 thread bar through all the courses except the top one and clamped it all tight, then just capped it off with a single course.
  19. LiviuM

    LiviuM New Member

    Hi Rusty. That's pretty much my plan apart from the metal bar. Instead, I'll be using oak dowels.
  20. FlyByNight

    FlyByNight Screwfix Select

    I made a similar suggestion earlier - it would be a better solution and could be driven into the ground. Threaded (or not) bar into a wobbly/enlarged/non-concentric hole would not matter, just use expanding Gorilla glue and it would be roack solid. A friend did one recently, with advice from me, and used 300mm screws, layer by layer, then on the top layer, a 25 mm deep counterbore and an Oak plug glued in and trimmed flush.

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