Thread: Saw handles

Bit of shame with the splintering Pac man. Looks more a technique problem. The scorch marks will normally indicate your forstner bit speeds too high. If so you will need to clean up the bits back to a smooth surface and try running them at a lower speed. If the splintering/tear out is happening to the underside of the handle blank, try drilling a small dia pilot hole so you can identify the centre point on each side of the blank and forstner half way down from each side. Good to see you making progress with the backsaw making. Best of luck.

Stewie;

Thanks Stewie for the feedback. Seeing the three of them together highlights the problem. The forstner bit is new and has smooth sides. There are some small black burn marks on the lands which I will show to the diamond paddle to clean them off. I will lower the speed and try the pilot bit as well.

I am not sure what thickness your starting at with your handle blanks Pac Man, but in my case if my final target thickness is 23mm my starting point for the handle blank is in the region of 24 to 25mm thick. That way I am allowing enough scope for later loss caused through repetitive flat sanding over different grits. This may sound a lot to allow for, but when you include the seating of the saw bolts just below the surface that are then later sanding flush, the total loss starts does mount up. I should make mention that the saw bolts I use are suited to a max of 23mm thickness handles.

Stewie;

Pacman,

The resin infusion I have written about decreases the splitting problem but does not eliminate it. By using a scroll saw to complete detail and interior cuts after roughing my handle blanks I have virtually eliminated the problem of splitting in my handles at this stage of production.

Cheers,
Rob

Set your stop so that the forstner bit point just pokes through the other side. Then flip the piece and bore from the other side. No more blow out. Best wishes, Ron

Hmm that pattern looks familiar

I agree with Ron's suggestion as it's what I ended up doing when I started my handles (well my second if you must know)
Ron makes it sound easy but you need to make sure that you allign the forstner up precisely with the small exit hole, can be fiddly DAMHIKT.

Firstly an acknowledgement is in order for Isaac Smith of Blackburn tools who allowed the use of the template for the workshop and I have used it again here. Thank you.

Today I bought a vintage disston backsaw at a tool sale. It prompted me to revisit the handles and muck around further and cut out the blown out section. I then looked over at my Wil-kut (Ian Wilkie) saw and coloured in the round overs in the similar places as Ian would have them. It may yet be saved.

Thanks to those who have answered with encouragement and thought. Stewie the blanks are 23 mm now so will need to make the next ones a bit thicker. Ron I will try that technique also. Rob I am not quite at the point where I can do the infusion technique.. Nick appreciate the input.

I think they are still worth persisting with. There are no hard and fast rules to the exact final shape, thickness etc. they are custom hand made saws after all.

The next step I would recommend is drilling the bolt holes followed by cutting the slot and the mortice. If you make a mistake with those it is better to do before all the work in shaping.

Good to see your efforts, keep at it.

Paul, just to be clear, are you talking about splintering/blow out/break out from the Forstner bits? Judging by the scorching I'll wager that it was a Cabetec supplied Chinese HSS Forstner bit - am I right? Furthermore, Blackwood ain't called black wood for nuthin' - it loves to burn under a router bit or drill. Blunt bits will also exacerbate burning.

I have always found that a virgin sacrificial piece of MDF under the job (very firmly clamped) prevents break out 100%. There must be no dust/chips, gap or wriggle room between the job and the sacrificial piece.

Apart from too high a speed, a major reason for scorching is a lack of chip clearance which doesn't allow the bit to breath and stay cool. Dust extraction with a shop vac goes a long way in assisting this (hence firm clamping so that your left hand is free to operate the vac nozzle). Another thing that assists greatly with chip clearance is drilling a few mm then retracting to pull out the chips, a few more mm, back out again. This becomes much more important as the hole becomes deeper and chips are harder to eject.

Tip speed of the bit is directly proportional to the diameter of the bit: at the same rpm, a 20mm bit has double the tip speed of a 10mm bit, so the rpm needs to be halved to get the same tip speed (circumference is 22/7*diameter).

Apologies if this is egg-sucking tuition!

EDIT: I meant to add that if the timber is scorching to that extent then it is highly likely that that drill bit will be bluing at the cutting edge and/or the cutting wings of a Forstner or Brad Point - that will knacker the temper, particularly in tool steel - less so in "proper" HSS.

Paul, are you coming to the GTG on the weekend? I'd be really interested to have a look at what you guys got up to at the workshop. Horrible, splintery blow out bits and all.

Thanks for your thoughts Dale.

FF the local supplier that you mention does not supply bits in 7/16. It is a LV bit. so yes it is HSS and probably of Asian decent. So you can only have half my money.it's not too disimiliar to the bit that IanW had at the workshop. Call me nuts but MDF is verboden but I take your point on supporting the work.

NCA only too happy to share. If heavens above is reading this perhaps he could bring a completed saw.

Originally Posted by Pac man

FF the local supplier that you mention does not supply bits in 7/16. It is a LV bit. so yes it is HSS and probably of Asian decent. So you can only have half my money.it's not too disimiliar to the bit that IanW had at the workshop. Call me nuts but MDF is verboden but I take your point on supporting the work.

Just had a look at the LV site - no mention of "Made in the USA" so definitely Chaiwanese. I have the same bit here so it'll be interesting to compare yours to mine (bring it with you).

Understand about the MDF, but there are other things you can use like chip board (particularly Melamine coated), piece of Scrapiata - anything flat and pretty smooth. If you have a depth control collar on your DP you can use MDF without actually drilling into it. Many times I have drilled a hole to the set depth limit, and at the bottom of the hole there is a loose disc of the "good" material - this is the back face of the job. The only hole on the MDF is from the point of the Forstner (I guess you're rightly concerned about MDF dust and it's hideous inclusions). I can get this same result with Brad Point drills as well (except it's a little ring rather than a disc).

Hi Pac Man. As a continuation on the discussion about the handle blank thickness I suggest the following as a consideration. If the timber is already dressed on both faces and flat sanded to a constant thickness. Pre saw bolt installation is ideal at 24mm. When installing the saw bolts keep them close to 0.5mm below the face surface on both sides. Best presentation is to sand the show side flush to the bolts. The saw nut side is up to you as I see it not being so critical to presentation. I just completed this stage on my latest handle and decided to keep this side 0.25mm below the surface. For initial flat sanding I start with is 150 grit. The thickness of the handle blank is now 23.25mm. As Dale mentioned what handle thickness to you decide to aim for is really up to you. Without trying to hijack your post I have included a couple of photo's I took today of the handle I am currently working on. It shows the saw bolts heads flush on the show side, and the saw nuts slightly below the surface on the other side. Hope this helps you along your saw making journey.

Stewie;

Thanks for sharing your process. Where do you source your bolts from or do you make your own?