UJK Parf Guide Mark II and loose fitting dogs

[wriv]

Hello!

I'm new to the forums and to the craft, but have been slowly building my MFT-style bench (Paulk Smart Bench) as a first project. I'm using the Parf Guide Mark II to make the dog holes and have been struggling with loose fitting dogs no matter what I try.

The dogs always have noticeable play in the hole. It doesn't take any pressure to seat them; there's enough play that they drop in from gravity alone. I reached out to Axminster and after a few exchanges, they sent me a new 20mm cutter that they tested before shipping. I was hopeful this would address the issue, but I get the same loose fit using both of the bits.

Here are 2 videos I recorded showing how the dogs fit (apologies if this isn't the best way to post videos)
https://d2dmppnfx8a8m8.cloudfront.net/parf/parf-loose1.mov
https://d2dmppnfx8a8m8.cloudfront.net/parf/parf-loose2.mov

I'm following the instructions for the system. The locator pins are fully seated when drilling the pilot holes. I use the pins to align the guide block and even clamp it down to make sure it doesn't lift or tilt while drilling. I'm drilling slowly and pecking as recommended.

I've tested the fit with both the included Parf Locator dogs and also with a pair of TSO Close Fit dogs. I measure dogs both to have a 19.95mm diameter.

I've also tested in a few different materials: Baltic Birch (12mm and 18mm), MDF (12mm), and MDO (12mm). Same result.

I've made sure to use both of the bushing in the guide block. Same result.

I've also tried chucking the bits into my Rockler drill guide to eliminate the guide block and drill runout as a factor. Same result.

At this point I'm questioning my expectations for the product (which seems excellent aside from this issue). Most of the reviews and tutorials rave about a snug dog fit with zero play (even too snug), but this has not been my experience.  To be fair, the loose fit I'm experiencing is probably manageable but I can't shake the feeling that something is off.

How snugly do everyone else's dogs fit in their PGS produced dog holes? Are my expectations the problem or is there some other factor I'm failing to account for?

Thanks in advance for any ideas or suggestions!

Will

 

[AstroKeith]

Hi Will & welcome.

I've used the Part guide to drill about 300 holes so am pretty familiar with it. Some other people seem to have trouble getting the 96mm spacing right, not so many on hole "snugness".

I can get a clean 'gravity drop' in about half of my holes, but then they are mostly well 'run in' by now. The new holes are more snug.

You're right to be careful on the actual dogs themselves.

Looking at your excellent videos I would say they are OK overall. The 'waggle' test you show isn't fair as so little of the dog is in the hole. Which brings me to my main point - the bench tops must be 18mm+ thickness.

Personally I dont care for the simple bench dog clamps that produce a strong levering action on the hole, even with a hold down knob. Bessey make a good clamp mounting plate that overcomes this issue.
Bench dogs work best with clear lateral forces against them and absolute tightness isn't critical.
You want them to be tight enough so that using dogs to set up a square cut is accurate. I think yours looked OK.

 

[wriv]

Looking at your excellent videos I would say they are OK overall. The 'waggle' test you show isn't fair as so little of the dog is in the hole. Which brings me to my main point - the bench tops must be 18mm+ thickness.

Appreciate the response! It had crossed my mind that the material's thickness could be a factor, but the few tests I did in 18mm material had the same results. Plus, the locator pins have all fit extremely snug in the pilots holes, regardless of the material thickness, so I didn't pursue this further. I may need to revisit. The majority of my tests since then have been in 12mm material.

Also useful to know that many of your dogs also drop in from gravity alone. Maybe my expectations need calibration more than my tools.

Thanks for the insight!

 

[mkasdin]

You can try using shellac in the holes. Don’t get overzealous.  Just a little and that will tighten the holes. The other thing I’ve done is put a single wrap of plumbers Teflon tape and the dogs will fit in snug. No jiggley dogs.

 

[Crazyraceguy]

Looking at your excellent videos I would say they are OK overall. The 'waggle' test you show isn't fair as so little of the dog is in the hole. Which brings me to my main point - the bench tops must be 18mm+ thickness.

Appreciate the response! It had crossed my mind that the material's thickness could be a factor, but the few tests I did in 18mm material had the same results. Plus, the locator pins have all fit extremely snug in the pilots holes, regardless of the material thickness, so I didn't pursue this further. I may need to revisit. The majority of my tests since then have been in 12mm material.

Also useful to know that many of your dogs also drop in from gravity alone. Maybe my expectations need calibration more than my tools.

Thanks for the insight!

That's really surprising. I have had/used the Parf-Guide system for so long that the MK2 system wasn't around yet. it has always been great. My main assembly table has 325 holes in 3/4" MDF and they all fit very well. None of mine will "fall in", they have to be pushed. I also have a side table that is used for cross-cutting with the UJK dogs. It is made from 3/4" melamine coated particle board. I insert/remove the rail dogs from the same holes quite frequently and no issues there either.
My bit has drilled a minimum of 500 holes and I have never had a loose one?

 

[seturner]

I am having this issue as well.  Does anybody experience play between the guide bushing and the 20mm cutter shaft?  I do and the shaft on my cutter measures 9.97mm.

I have reached out to both Axminster and TSO.  TSO is going to send me a new cutter whenever they get stock.  Axminster says they cannot send me one due to customs and tax.

I suspect the spike on my cutter is a little off center or bent. When I first begin drilling the 20mm holes using the guide, the drill and cutter wobble some when the cutter engages the mdf, or it could be due to the play between the guide bushing and the cutter shaft.

Regardless, my TSO close fit dogs are loose in most holes.

 

[Birdhunter]

Is it possible that the people with loose holes are using a drill with too much runout?

 

[Roachmill]

I suspect the spike on my cutter is a little off center or bent. When I first begin drilling the 20mm holes using the guide, the drill and cutter wobble some when the cutter engages the mdf, or it could be due to the play between the guide bushing and the cutter shaft.

Just checking the basics here - are you drilling the 3mm guide holes first (the ones done with the rulers and guide bush) before using the 20mm cutter? the point on the 20mm bit is supposed to have the holes there to guide it through and I'd imagine without them it would have all sorts of problems.

 

[seturner]

Is it possible that the people with loose holes are using a drill with too much runout?

I wonder that as well.  I am using a Milwaukee M12 Drill/Driver with Hammer functionality(No, I am not using it in Hammer mode LOL).  The drill is a bit crude.

However, when drilling the 20mm holes, since the drill is heavy, I make sure the drill body is aligned with the jig so that if it trys to tip, the weight is along the jig and not across it.

 

[seturner]

Just checking the basics here - are you drilling the 3mm guide holes first (the ones done with the rulers and guide bush) before using the 20mm cutter? the point on the 20mm bit is supposed to have the holes there to guide it through and I'd imagine without them it would have all sorts of problems.

I am indeed using the rulers and drilling the 3mm guide holes.  I am positing that the spike is a little off and since the cutter is constrained by the guide at one end and the spike in a 3mm hole on the other, that an off center or bent spike can cause an eccentric motion on the cutter resulting in a slightly larger or non round hole. 

 

[Michael Kellough]

I wonder if everyone with this issue are using Part Dogs. Not all dogs are the same size.

 

[seturner]

I wonder if everyone with this issue are using Part Dogs. Not all dogs are the same size.

I for one experience the loose fit with the included locator dogs as well as the tso double groove close fit dogs.

 

[hoe]

I just finished my top using the Parf Guide. When i experimented with my Milwaukee drill i found it a bit top heavy so i ordered a CXS and oh what a difference. But i think the Milwaukee would have done the job. One thing about the Axminster parf dogs with the chamfered collar it allows them to seat properly without any wiggle and they are solid. I tried a 20mm pin which came with my Insta Track Square and they were a little loose in the holes for sure. When i ordered my guide i did order a pair of tall and a pair of the short dogs.

 

[hoe]

I wonder if everyone with this issue are using Part Dogs. Not all dogs are the same size.

I for one experience the loose fit with the included locator dogs as well as the tso double groove close fit dogs.

For those with the wiggle issues i'm just wondering what would happen if you put a coat of lacquer or such to the parts of the dog that goes into the hole and of course let it dry and then see if you get the fit you are after? … just a thought. Not sure if lacquer would stick but anything is worth a try … even clear nail polish?

 

[Rick Herrick]

I just finished my top using the Parf Guide. When i experimented with my Milwaukee drill i found it a bit top heavy so i ordered a CXS and oh what a difference. But i think the Milwaukee would have done the job. One thing about the Axminster parf dogs with the chamfered collar it allows them to seat properly without any wiggle and they are solid. I tried a 20mm pin which came with my Insta Track Square and they were a little loose in the holes for sure. When i ordered my guide i did order a pair of tall and a pair of the short dogs.

I bought my MKII about a year ago based on videos by Peter Parfitt.  I bought the CXS simply because I saw him use it and it worked great.  No regrets.

 

[hoe]

I just finished my top using the Parf Guide. When i experimented with my Milwaukee drill i found it a bit top heavy so i ordered a CXS and oh what a difference. But i think the Milwaukee would have done the job. One thing about the Axminster parf dogs with the chamfered collar it allows them to seat properly without any wiggle and they are solid. I tried a 20mm pin which came with my Insta Track Square and they were a little loose in the holes for sure. When i ordered my guide i did order a pair of tall and a pair of the short dogs.

I bought my MKII about a year ago based on videos by Peter Parfitt.  I bought the CXS simply because I saw him use it and it worked great.  No regrets.

Right on Rick! I am certain enjoying both purchases.

Regards Wayne

 

[Cheese]

I am positing that the spike is a little off and since the cutter is constrained by the guide at one end and the spike in a 3mm hole on the other, that an off center or bent spike can cause an eccentric motion on the cutter resulting in a slightly larger or non round hole.

The center point pilot/spike of the Forstner bit will not cause an oversized hole. The Forstner bit will be guided only by the Oilite bushing and the diameter of the hole will be determined by the OD of the Forstner bit. I’d check the Forstner bit closely for burrs or rough edges/areas. It doesn’t take much to cause an oversized hole.

 

[seturner]

Please watch linked video of me demonstrating my 20mm cutter.

At the beginning, I spin the cutter without the bit touching the mdf.  I then engage the spike of the bit with the mdf.  Finally, I actually drill into the surface.

 

[Cheese]

Ya, I understand completely what you're saying  [smile] , but there's no way that a 1/8"-3/16" diameter centering point when engaged in wood will overturn the centering of a 1/4"-5/16" shaft when constrained within an Oilite bearing. I think the issue is cutting spurs that are not concentric or an Oilite bearing that is not within spec. The cutting spurs would make the most sense because when engaged with the wood, the mechanical advantage is such that they would indeed dictate what path the Forstner bit will take.

The good news is that there seems to be no movement with the Parf Guide, that's a good thing and one less thing to worry about, the pins appear to hold it solidly in place.

I'd focus on the spurs or the Oilite.

 

[squall_line]

FWIW, on my CXS, I almost always pull the trigger with my middle finger and stabilize the body of the drill with my index finger.  This also puts the meat of my hand closer to the centerline of the drill bit for less off-axis pressure.