# can't get them perfectly lined up



## allnew (Jan 14, 2015)

I've attached a pic for illustration. It's getting better, but I am still struggling to get the edges to line up perfectly( see the left corner). Since these parts are cnc cut, they are dimensionally precise. I intentionally use a 1/8" clearance hole for #4 sheet metal screws to provide some hole clearance, and use a 90 degree jig and a strap to align the corners before I drill the pilot holes. For the pilot holes , I use a small broken PCB drill with a 1/8 shank to make sure that the hole is perfectly??? centered.

No luck. When I am done the panels are always a bit off.

The variable is, of course, that I hand drill the pilot holes and the jigs still require some fiddling. I use the panel holes to drill the screw holes. If my hand is crooked, so will the hole. Making a hole jig has been daunting, given the sizes I'm working with. 

Since I am trying to make production runs, I cannot afford to baby sit each hole. I have to be fast. 

It's a combination of lack of technique and good jigs, but what are they?

thanks
tony


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## difalkner (Nov 27, 2011)

Quick question - if you take the screws out does the panel line up correctly? If so, when you put the screws in one at a time can you determine which hole pulls it out of registration?


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## Steve Neul (Sep 2, 2011)

It sounds like woodworking to me. If it was a solid material like plastic you could precisely drill a hole where you want. With wood you may have the drill set up perfect but the bit is going to have a tendency to follow the soft grain of the wood throwing the hole off a little.


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## allnew (Jan 14, 2015)

difalkner said:


> Quick question - if you take the screws out does the panel line up correctly? If so, when you put the screws in one at a time can you determine which hole pulls it out of registration?


My procedure is to line up the(2) panels's edges with one right angle jig. I feel the surface by hand, tighten the jig well, and then drill the pilot holes. Since this is MDF and one panel with the existing holes prevents me from drilling the holes deeper, I then remove the panel with the holes and drill the holes a bit deeper( all by hand).

From here on, when I go to attach the panels, they are a bit off.

I know that I am dealing with a "slippery" material, but I am selling a product that's need low material costs, so MDF is the natural choice. Of course, if someone had a better material in mind that competes very favorably with MDF( 3/8 and 1/4), I would consider it. 

I keep thinking that a series of steps, including some proper jigs should make this doeable. 

i am tempted to make the top panel holes a big larger, so that the panel can be aligned manually after the screws have been added. I am not sure if this will create other issues, or it's a sound professional approach.
Lastly, to answer you question, I am not sure. I drill one side at a time and after all the panels are fastened, something is always a bit off.

One idea I have is to drill some location holes on the inside panels and then make a jig that helps align or keep the two panels lined up.

One more thought..... I am using the right angle jig purchased from HD. It's more solid than , let's say, Harbor Freight, but I am wondering if the fact that these are cast and not machined might have some built in error.

Anyway, I am confident that I'll get closer to perfection. Just answering these posts keeps me thinking about various improvements..
tony
tony


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## TimPa (Jan 27, 2010)

you may consider some type of clamping arrangement to hold them in place as you drill them and then as you attach them. or you could tack with a pin nailer to hold as you srew. holding by hand is tough to accomplish perfection with, esp screws.


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## SteveF (Mar 20, 2014)

You may be able to drill and countersink the panel, put it in place and use a self centering drill to drill the screw holes.

http://www.amazon.com/gp/product/B0..._m=ATVPDKIKX0DER&pf_rd_r=01P7WXVZPBZ7PG9F5KF4


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## firehawkmph (Apr 26, 2008)

Ok, I give up. What is it?
Mike Hawkins


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## Hammer1 (Aug 1, 2010)

"My procedure is to line up the(2) panels's edges with one right angle jig. I feel the surface by hand, tighten the jig well, and then drill the pilot holes. Since this is MDF and one panel with the existing holes prevents me from drilling the holes deeper, I then remove the panel with the holes and drill the holes a bit deeper( all by hand)."

BINGO!! The second drilling operation is off. You need to do it in one operation through one part into the next while things are clamped, not hand held. Can't see why you would need any drilling jigs other than to mark the screw positions. Hand drill, drive the fastener, done. All you need is the correct drill bit/countersink combination and the correct fasteners for MDF, which are not sheet metal screws.


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## woodnthings (Jan 24, 2009)

*make a drill template*

Use a piece of sheet metal or plastic or aluminum with small holes to get your pilot holes located. Just predrill 1//16' hole and follow up with your pilot holes for the screws.


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## BWSmith (Aug 24, 2010)

As a small production shop you need to develop a protocol system of "thinking"......planning would be another adverb.

Looking up at the responses,your question/s have been answered.

Once you start practicing,"I can name that tune in ? notes".........as it applies to working out a schedule or plan of attack for a given project or task....the easier it gets.Like playing scales on a piano,it's hard at first....but keep practicing and it gets to be second nature.So it is in the setup and sequencing in a production shop.

You need to do that drilling AND fastening job with the least number of physical "moves".Again,your questions have been answered above,IMO.The only thing I can add is that sometimes......even though you have a working protocol,you might want to practice on some scrap pcs to work out any unforeseen problems.Could be sumthin as simple as drill geometry?

Best of luck,back to regular programming(ha).


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## allnew (Jan 14, 2015)

SteveF said:


> You may be able to drill and countersink the panel, put it in place and use a self centering drill to drill the screw holes.
> 
> http://www.amazon.com/gp/product/B0..._m=ATVPDKIKX0DER&pf_rd_r=01P7WXVZPBZ7PG9F5KF4


I've just ordered this item; it looks promising. thanks
tony


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## allnew (Jan 14, 2015)

firehawkmph said:


> Ok, I give up. What is it?
> Mike Hawkins


it's the shell for a flight simulator throttle quadrant for the hobby market.
tony


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## woodnthings (Jan 24, 2009)

*Is the issue getting it square or drilling the holes?*

If that is the problem, make a "certified" square base to clamp the pieces to. Maybe a "captured" assembly fixture where the pieces can't move like in slots or surrounded by small strips. Then it will always be square when you assemble it. It will take some time and patience to make this, but you will save time in the long run for production.

If the issue is accurately drilling the holes, like I said make a "drill template" with 1/16" hole to predrill for your pilot holes. 

:smile:


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## allnew (Jan 14, 2015)

woodnthings said:


> If that is the problem, make a "certified" square base to clamp the pieces to. Maybe a "captured" assembly fixture where the pieces can't move like in slots or surrounded by small strips. Then it will always be square when you assemble it. It will take some time and patience to make this, but you will save time in the long run for production.
> 
> If the issue is accurately drilling the holes, like I said make a "drill template" with 1/16" hole to predrill for your pilot holes.
> 
> :smile:


Can you elaborate a bit more on this "certified" square base and "captured" assembly fixture?
I am intrigued by this, and it sounds like what I need to do.
thanks
tony


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## 4DThinker (Mar 13, 2013)

When back on the CNC those 1/8" holes could have been cut. There are 1/8" diameter spiral bits out there 5/8" long. If the CNC had a 1/8" chuck a conventional 1/8" drill bit could have been used as well.


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## woodnthings (Jan 24, 2009)

*"certified" assembly fixture*



allnew said:


> Can you elaborate a bit more on this "certified" square base and "captured" assembly fixture?
> I am intrigued by this, and it sounds like what I need to do.
> thanks
> tony


That would be rectangular box with all 4 sides square to each other, tested and certified by you as such. Precisely laid out to the dimensions of your final product, then screwed or glued in place on a piece of substrate like MDF or 3/4" hardwood plywood. 

Once the box is in place with a 4" border or around it, locate some 3/4" thick strips around it the distance away the thickness of your workpieces. Place a sample piece on the sides of the box, locate the strip against it and screw it down. 

Now you can place your pieces inside the strips and against the box to locate them precisely. A few clamps lightly applied should maintain their position for the next operation which would be screwing on the top pieces.

I would pre-drill the tops with a drill template, then use them to pre-drill on the edges. the holes should be sized for the screws you use. Make test holes to get it exactly right size. Use the appropriate size screw with coarse threads for the MDF. Screwing into the edges of MDF is a bit risky as there is no real wood, only composite. If the final product is subject to any abuse in handling or if dropped the joints may not hold.

Sheet metal screws should be fine with countersunk heads....another operation, best done on a drill press with a stop on the feed for uniformity of depth. Some countersinks have a depth limiter built in, if you don't have a drill press.

Now you have a "foolproof" way of assembling this product with little or no variation. All the corners should be square at 90 degrees, but it will only be as precise as your fixture is square.

Do take some build photos as you go to post here!


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## allnew (Jan 14, 2015)

4DThinker said:


> When back on the CNC those 1/8" holes could have been cut. There are 1/8" diameter spiral bits out there 5/8" long. If the CNC had a 1/8" chuck a conventional 1/8" drill bit could have been used as well.


The holes are drilled on the cnc. These holes, however, apply to only one panel, which is used as the template for drilling the matching holes. 
tony


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## allnew (Jan 14, 2015)

woodnthings said:


> That would be rectangular box with all 4 sides square to each other, tested and certified by you as such. Precisely laid out to the dimensions of your final product, then screwed or glued in place on a piece of substrate like MDF or 3/4" hardwood plywood.
> 
> Once the box is in place with a 4" border or around it, locate some 3/4" thick strips around it the distance away the thickness of your workpieces. Place a sample piece on the sides of the box, locate the strip against it and screw it down.
> 
> ...


Thanks for the more clear explanation. This is a good idea that I'll start working on, and follow pictures.
thanks
tony


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## allnew (Jan 14, 2015)

The nice thing about having a cnc machine is the way you can test new ideas with precision. Taking into account all the good observations made to my questions, I am designing an "assembly box" with pre drilled locating holes that will be on the "inside" of the shell. I will also partly drill matching locating holes on the panels that will allow me to screw the panels to the "assembly box". If the design is correct, I should be able to line up the panels just by placing them against the "box" and then screwing them to the box. If needed, I will then make additional "outside" holding strips for additional support.

I am hopeful that this will bring me closer to "perfection".

One observation that was also made was regarding the hole sizes on the panels. I assumed that they had to be a bit larger than the screw diameter in order to provide some "wiggle" room to compensate for the various variables. It was suggested that I make the holes the same diameter as the screw. I'll see how that works out. Stay tuned.
tony


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