Author Topic: HK85 grooving unit opinions  (Read 656 times)

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Online Roachmill

  • Posts: 156
HK85 grooving unit opinions
« on: June 19, 2019, 04:22 PM »
I have an HK85 en route and I'm wondering about the practicality of the grooving unit; not for construction work where a few mm here or there is fine but I'm wondering how it would work like a dado stack on a table saw for things like cabinets. I'm in the UK where such things aren't at all common... and I don't have a table saw, so I'm all ears.

With my experience of blade Vs track splinter strip offsets varying due to different kerfs, does the grooving unit share the same offset as the stock 85 blade? I already have 2 sets of tracks for the TS 55 and 75 because of this (and an HKC which is more offset than either of those). So, were the grooving unit another offset to handle, it'd not be all that quick to align for precise dados.

From the videos I've seen, it appears to leave a pretty sharp and crisp edge on the face of whatever it's ploughed its way through. Here I'm wondering whether it's up to shelf housings and rebates (rabbets) in ply / MDF. I have a sneaky feeling this isn't the type of work it's designed for!

It wouldn't have anywhere near the precision for setting depth of cut as a router, which could be a bit of a problem but not insurmountable. Possibly. Any tips on precisely setting the depth of cut?

As I said, I'm looking at it for purposes it's not intended for. But any input from anyone with experience of using it would be appreciated either way.
« Last Edit: June 20, 2019, 08:06 AM by Roachmill »

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Online Roachmill

  • Posts: 156
Re: HK85 grooving unit opinions
« Reply #1 on: July 26, 2019, 12:48 PM »
I bit the bullet and bought the grooving unit thanks to being a weak, easily lead individual and an eBay 20% off promo. For reference purposes I'll attempt to answer some of my own questions.

The offset is pretty much nuts-on to my TS75 with the 2.6 kerf panther blade. I'm not going to attempt aligning all saws to work off the same rails as I've been there, done that and bought an extra pair of rails at the end of it.

The cut quality with a brand new out-of-the-box unit was surprisingly good. Certainly equal to what I get from any router with a good bit in it. The bottom of the trench in MDF was actually crisper. VN on the left and router on the right:

Cutting 18x10mm in one quick pass really was quite satisfying :D Using a D36 hose caught most of the dust too so no complaints there.

Depth setting wasn't great... but that's true of other saws where it rarely cuts exactly what you've set it to. With the unit being a smaller diameter than the normal blade, you have to work off a conversion scale on the unit guard. Set it to 60 for a 10mm depth cut it said. 61mm got me 10mm.

Another niggle was the width of cut. It has a bunch of spacers to go between the two halves of the block itself. No spacers is meant to get you 16mm so I added a 2mm spacer to get me up to 18mm. That turned out to be about 18.8mm. The 18mm (3/4) MDF I have access to is usually around the 18.3mm mark so that leaves too much wiggle room for my liking. It was never going to be spot on in that regard, so no biggy as 2 passes and some wee spacers should do the trick.

The HK won't fit in the systainer with the guarding fitted (the dust port sticks out too much) meaning you have to either take it off (and find a home for the normal blade and other bits) or completely swap everything back for normal sawing operations. That will get old. I may look at modifying the SYS1 the unit comes in to house the blade and other bits.

Also, the guarding with the dust port flexes more than I'd like when taking the hose on and off. It certainly feels like you need to take care when removing it.

All grumbles aside, it's a keeper :D