Reboring Dogholes - Thoughts ?

jfynyson

Jeremy
User
A few months ago I built a MDF (4 layers of 3/4") work bench to have a flatter & much sturdier work surface than I had before. It's been wonderful working on but I messed up drilling by hand a few of the dog holes & holdfast holes. I believe part of the issue was using very old/dull 3/4" forstner bits and pushing too hard led to off square holes. I now have a Rockler Portable Drill Guide and a new 3/4" forstner bit by Fisch. You can see the issues in the pics below. The dogholes being slightly off are not that bothering to me but the planing stop hole (my first hole) is off such that the stop bows up on the far end (this can cause issues on planing thin stock). The baltic birch planing stop is flat and lays fine (as does my other stops I made) otherwise so it's that hole. That one holdfast hole pic'd below is really jacked up.

Questions
  1. Being MDF what's the likelihood of success if I could glue in some 3/4" poplar dowels and then bore fresh holes in the same spots ?
  2. Would the MDF soak up too much of the glue around the dowels thus causing tear out upon reboring the holes resulting in even worse holes ?
  3. Also, the oak dowels/dogs were super tight a few months ago and several now just basically fall through. I added some paste wax and this has helped a bit. Do you feel this is simple seasonal humidity issues and it'll be ok in the spring/summer & fall ?
Left planing stop hole/dog hole being off creates the right side stop lift.
IMG_9822.JPG


Jacked up holdfast hole
IMG_9824.JPG


Dogs slipping down too easily now when they didn't do this a few months ago. I've not really used these holes yet either. Wax helped but thinking this is just seasonal movement of the dogs
IMG_9823.JPG


The right tool for the job is now mine !....I knew I needed this before I built this workbench but my b-day was not soon enough for my need of the bench.
IMG_9827.JPG


It's a 28x48" bench on flip up casters with repurposed pine base. Moxon style end vise is ambrosia maple and the backer is white oak. I love the sturdiness & weight when planing & chopping.
IMG_9825.JPG


Workbench also doubles as the kids school bags hanger and storage bins.
IMG_9826.JPG


Many thanks in advance !

Jeremy
 

gator

George
Corporate Member
Just my opinion, but I think that MDF makes a fine worktop if you don't drill it. It is too brittle for holes which will have side pressure on them. Think raw edges on the MDF and how quick they would crumble.
 

Oka

Casey
Corporate Member
Usually people make these kind of tops with the surface layer replaceable Is that not the case ?

This might sound crazy, but maybe you could prep the surface, plug the bottom of all the holes and then resin the whole thing filling all the holes. Then re-drill the holes, fine sand and buff out.

Another Idea could be to use Valchromat, which is colored MDF with more resin glue in the mix, it is less dusty and is harder. There is a vendor in Mt Airy :

Ph. 336-786-6254 | ForesColor USA | 391 Hickory Street | Mount Airy | NC 27030. ·

This is basically the same stuff as Valchromat.
 
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jfynyson

Jeremy
User
Thanks for the thoughts (maybe I missed your points) but the issue here is mis-drilled initial holes (not all of them) on my part. The others work perfectly. The idea/concept of the MDF top with dog holes came from Rob Cosman’s design after a lot of use/testing over the years so I am not questioning the thick MDF top being the problem for dog hole use.

I didn’t mention this but the bench is in my living room (only place I can do this kind of work right now) so an epoxy pour idea for each hole is something I thought about but not only would that cost more than my bench (a budget/scrap wood bench for a reason) but me and the family couldn’t deal with the epoxy odors. The 5min epoxy could be a try (cost-wise) for the planing stop hole alone but even then the odor would be too much unfortunately.

I’m just wondering if the bad holes are fixable if gluing in dowels then reboring and if the dog holes that have not been used all of a sudden see the dogs lose is simply due to seasonal change in the oak dowels.
 

Mike Davis

Mike
Corporate Member
I would drill oversized like 2 or 3 inch holes to repair the misdrilled ones.
Glue in a dowel to fit, let dry well, then drill the 3/4 inch hole in the dowel.

This will be stronger, cleaner, and more accurate since you won’t have the old hole guiding the bit.
 

Scott H

Scott
User
Regarding bench dogs falling out, mine have bullet catches installed in them so the dog itself is always undersized and the spring in the bullet catch stops them from dropping out the bottom. Seasonal movement is definitely enough to change them from snug to loose fit.

Edit: You could also experiment with just putting masking tape on the dogs to see if they snug up. I'm sure it would want to come off with use but there might be an arrangement that holds up enough to get work done.
 

Alan in Little Washington

Alan Schaffter
Corporate Member
It must be me, but I don't understand the issue- Is it you are bothered by the esthetics - the holes aren't perfect? Or is it that the dogs do not slide in the holes properly?

If the dogs work like they are supposed to in the existing holes leave them alone.

If the dogs are too tight because the holes are offset, top to bottom, or curved and the dogs don't fit or slide properly- drill out the existing holes to the proper diameter.

If the dog holes are too loose- put a bullet catch, metal spring, or wood spring on the dogs. If you don't want to modify your dogs, you can tighten the fit by narrowing the dog hole slightly- glue in a wood splinter, paint the inside of the hole with a thin paste of sawdust and glue, etc.
 

Oka

Casey
Corporate Member
ANd I thought I was bad, you got us all beat. The work table in the living room ........ :oops: :D


I didn’t mention this but the bench is in my living room (only place I can do this kind of work right now) so an epoxy pour idea for each hole is something I thought about but not only would that cost more than my bench (a budget/scrap wood bench for a reason) but me and the family couldn’t deal with the epoxy odors. The 5min epoxy could be a try (cost-wise) for the planing stop hole alone but even then the odor would be too much unfortunately.
 

marinosr

Richard
Senior User
Good advice here. I like Mike's plan. Since you'll be drilling into end grain go SUPER slow... You can scorch your nice bit very easily.

Mostly dropped in to offer this bit of hard won advice... If you ever want to have a holdfast on your bench, never NEVER use wax in your dog holes. The holdfasts won't hold fast because of the reduced friction. Danmart77 and I both made this mistake and really regretted it. I had to resort to scrubbing the inside with solvents and a bottle brush, but would not recommend that with MDF or in your living room. If wax had only been on the dogs you may be ok if you make new ones. A slightly undersized dog (quick sanding) plus a spring as shown below (or a ball catch suggested above) is the way to go. Of course there's no problem if you don't use a holdfast.

As a formerly closeted woodworker (as in every tool I owned had to fit in our dining room coat closet) I see you trying to make it work in difficult circumstances!
 
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kserdar

Ken
Senior User
MDF holes can be "hardened" with super glue.
You can tap MDF holes after soaking in super glue.

Seems like you would be using a lot of super glue.
 

jfynyson

Jeremy
User
I appreciate all of the feedback / suggestions. For the slightly loose dogs I'll first try the tape idea and wait to see what happens in the spring or if I get tired of it get those bullet catches. Also thanks for the wax / holdfast watch out. If I ever decide to use the holdfasts in the dogholes I'll be sure to remove the wax first ! I'm still not sure how I want to tackle the plane stop doghole as really it's an aesthetic issue and boring a much larger hole while it would be better option, it would look worse in the end than dealing with the slight lift the hole now causes for the far side of the plane stop.
 

Hmerkle

Hank
Corporate Member
@jfynyson I woudl be tempted to use the Rockler Portable Drill Guide and redrill the suspect hole for your planing guide to see if that alleviates the bowing problem. Obviously a first step since the alternative is to "fill" the hole and redrill. So if that doesn't work, you still have to rework the top...
 

jfynyson

Jeremy
User
@jfynyson I woudl be tempted to use the Rockler Portable Drill Guide and redrill the suspect hole for your planing guide to see if that alleviates the bowing problem. Obviously a first step since the alternative is to "fill" the hole and redrill. So if that doesn't work, you still have to rework the top...
Good call for sure
 

Hmerkle

Hank
Corporate Member
Good call for sure
I would probably mount the Rockler Portable Drill Guide on a piece of plywood and (CAREFULLY) measure off the distance from the other dog hole.
Drill a reference hole (tight 3/4" hole) to match a dog and then mount the Drill Guide on the center of the other hole.
 

jfynyson

Jeremy
User
Follow up/status:
Just a small sliver of blue painters tape on the loose dogs seems to work perfectly to tighten them but still allow them to function moving them up & down in the doghole.

The Rockler Drill Guide has indexing pins you can use to register sides of the substrate it sits on. Fortunately the distance from one pin to the center of my dogholes (from the side of my bench) was the perfect equal distance so I rebored the plane stop hole and it was indeed off by about 1/16" near the bottom of the hole and now my plane stop lays flat !

I've not done anything with the holdfast holes...will need to use them more to see if they are truly an issue. Fortunately I just started a new project where I'll get to test this all out.

Many thanks again for all of the input/suggestions !
 

Hmerkle

Hank
Corporate Member
Thanks for the update Jeremy.
I think 90% of woodworking is figuring out how to fix your mistakes - at least that is true for me!
 

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