I need some aluminum machining help

[MarkE]

So here's the deal. I received a router lift for Christmas but I want to swap out the router plate for an Incra MagnaLOCK router plate. I already have the Incra plate and a full set of the magnetic inserts for it. The problem is the way the lift mounts to the plate requires some precise machining.

There are four through holes that need to be countersunk on the top side. These should be pretty easy and I can probably do them myself without too much difficulty.


On the bottom are some recesses and nine tapped non-through holes. I have no idea how to make these and get them in the exact correct positions relative to the center hole, and each other.


Anyone have any ideas on how this can be done correctly? Or maybe you know of a machine shop that can do the work?

 

[Skymaster]

Are you trying to duplicate one face onto the other? I CAN PROBABLY help if I knew own exactly what the plan is.

 

[ehpoole]

I have made templates like that before and the best way that I know to get everything aligned perfectly is to design your layout precisely as you want/need it in CAD and then print the drawing out as a 1:1 template (and measure to double check that your printer really prints 6"=6" on both axis as not all do, in which case you would need to tweak the print scaling in your CAD software to get a 1:1 print).

Once you have done that you can simply tape or glue (using removable glue) the paper template to your stock. The use either a center punch or a small wire gauge bit (day a #60 for example) and very accurately center such on each of the hole's center point crosshairs, these will guide your drill bits when you go to drill the holes later, stepping each hole up to final dimensions in several steppings if accuracy is critical.

Regarding the tapped non-through holes, you will wish to evaluate whether or not they really need to be non-through holes as that will complicate things unless your stock is much deeper than the bolts. If it is Ok for them to be through holes then make them such as it will simplify your life. Otherwise you will have to carefully drill them to depth, remembering to allow for the lost depth due to both your drill bit point and the starter threads on your taps, and if you do not have a lot of added depth then you will need a bottoming tap in addition to your normal tap with starter thread (the bottoming tap will have just a single starter thread, at most -- there are actually three types of taps defined by how many tapered starter threads they have).

Woodworking tools (tablesaw, bandsaw, circular saw, drill press, router, etc.) can actually machine nonferrous metals like aluminum so long as you take much smaller/shallower bites then you are accustomed to in wood (if you have ever worked extremely hard woods aluminum kind of behaves similarly). Just wear long sleeves with tight cuffs and possibly some disposable gloves because the waste that comes off is rather hot and will startle you if you are not expecting it, covering up skin in a safe manner (nothing loose fitting) will avoid that surprise.

Or you can ask most any machinist to make the part you need provided you can provide either accurate drawings or an existing template to copy from for their reference and clearly document any changes you want in precise language or drawings.

 

[MarkE]

Are you trying to duplicate one face onto the other? I CAN PROBABLY help if I knew own exactly what the plan is.

Yeah, my post is a little unclear.

The pictures are all of the mounting plate that I removed from the new router lift.
The first picture is the top side of the plate.
The second and third pictures (same view, one with flash) show the bottom side of the same plate.

My plan is use the pictured plate as a template and duplicate the recesses and holes on a second router plate so that I can mount the lift onto the second plate.

 

[MarkE]

Ethan makes a good point about the tapped holes. They can all be through holes, shouldn't have any major affect on the top surface of the plate as long as the holes are de-burred.

 

[Skymaster]

totally agree PLUS being thru a longer screw is not going to be a problem

 

[MarkE]

Looks like the three large round recesses should also be relatively easy. Two are 1-1/4" diameter and the smaller one is 3/4" diameter. I'm guessing I can drill those with forstner bits? Will HSS bits work or should I use my carbide tipped forstners?

That just leaves that rectangular recess around the 3/4" hole. It is accepts a 1/16" thick brass or bronze rub plate(?) that has to sit flush with the bottom surface of the router plate.

 

[Skymaster]

hole saw much better in metal. For recess I would make a router jig,depending on the corner radius required for bit size. Plunge a bit in ez steps until required depth is reached.

 

[ehpoole]

Looks like the three large round recesses should also be relatively easy. Two are 1-1/4" diameter and the smaller one is 3/4" diameter. I'm guessing I can drill those with forstner bits? Will HSS bits work or should I use my carbide tipped forstners?

That just leaves that rectangular recess around the 3/4" hole. It is accepts a 1/16" thick brass or bronze rub plate(?) that has to sit flush with the bottom surface of the router plate.

I would be concerned about a Forstner but taking too big of a bite in metal as they have a lot of contact area and relatively narrow shanks to transfer that power.

I go go about such by making a template in either wood or plastic (at least ~1/4") and then use either a pattern bit or a spiral/straight but (one that can plunge) with a bushing (with the template properly sized if using a bushing). You can then align the template and secure it in place using your boat holes and slowly begin machining the hole. Stick with 1/2" shank bits if you can as the added strength will reduce your risk of breaking the bit if you get a little over aggressive, but start out removing just a couple hundredths of an inch per pass until you get a feel as to what your bit and router can handle, backing off if things seem to be biting in too much. It takes awhile and sometimes it helps if you can slow your router's speed a bit to name handling a little easier, but those are parameters you can experiment with to find what works best for you.

I would suggest that your very first experiments be in some scrap aluminum just so that you know what precisely to expect as it is a little different than working with wood, though I have had some woods like Purpleheart that remind me a lot of working aluminum (except that aluminum does not split the piece if the bit catches!) in that they have to be worked very slowly with very shallow passes, particularly when making a trapped non-through pass. But this is a process where patience wins the game, so take things slowly and stay well inside the box that preserves your ability to maintain good control rather than getting aggressive and in a hurry.

At the same time, you may also wish to ask a CNC machinist what it would cost to make your piece as I would imagine it would not take much time to produce on a CNC once the CAD drawings were properly designed so that all they need do is specify depth of each cut (if the drawing is 2-D, 3-D would already have depth defined) and properly size the bolt holes to receive tapped threads since that requires slightly undersized holes to receive the tap.

Whichever way you go, good luck and update us on your progress!

PS -- The rectangular section would be done just like the circular sections, with a pre-made template and pattern bit to transfer such, with the template held in place via the bolt holes on either side. I would probably use a scrollsaw and file/rasp to make the square cutout accurately in the template -- cutting just shy of the lines and then finishing to the line with a rasp. The radius end corners will require using a bit of the same radius (or the corners could be predrilled with a drill bit of proper radius before milling begins), though if done with a router bit I would remove most of the material with a larger 1/2" shank bit, then come back with a narrower bit just to touch up the corners and make the final corner radius rather than trying to use the narrow but for all the material removal.

 

[Gofor]

When machining aluminum, you need plenty of lubricant and a slow bit speed to prevent galling. Too much heat and the aluminum will melt and smear over the cutting edges, rendering them useless.

Go

 

[ehpoole]

When machining aluminum, you need plenty of lubricant and a slow bit speed to prevent galling. Too much heat and the aluminum will melt and smear over the cutting edges, rendering them useless.

Go

I have often found that reducing the router speed helps a great deal, as does reducing the amount of material you try to remove in a pass. If you get that right then you do not necessarily need lubrication for aluminum since it greatly reduces the heat generated and thick aluminum pieces are pretty good at wicking away a lot of excess heat, though often the very thin edge at the surface may need to be deburred afterwards if the aluminum flowed a bit since that area has very little surface area to wick heat away (just like one has to be careful of blueing the tip of a chisel when using a grinder as the very thin tip has very little area to transfer heat back into the main body). But if you do need lubricant then wax (even a candle, and beeswax can be especially nice since it is tacky) works nicely and does not get nearly as messy as some oils, just smear the block of wax on the surface of the aluminum and onto the cutting and rubbing edges of the bit (with router turned off). You can also spray the bit with silicone for aluminum cutting, but then there is some risk of the silicone fouling a future finishing project if the bit is later reused (though some follow up routing in a piece of scrap wood is pretty effective at wearing off the silicone on the bit's leading edges, so that is also an option to reduce the risk of fouling future projects.

But whatever you do, the material you are milling away will be uncomfortably hot if it hits bare skin, so cover up bare skin with tight fitting clothing and gloves (though I suggest disposable gloves if ther is any chance of your hands coming near the bit as cloth can get wrapped up in a bit, drawing one's hand into the bit if you get too close). It does not take much of a barrier to protect you from the hot waste material, in fact, the protection is as much to avoid distracting the operator as it is actual protection as the waste is in contact for such a brief period that you will not be burned, but it can be very uncomfortable, even startling if unexpected. But that is part of why I suggest the first practice be in some scrap aluminum so that one knows exactly what to expect before tackling the real project if one has never milled aluminum with woodworking tools before. It gives you a real chance to understand the process without having to stress if you make any mistakes.

 

[Gofor]

Good post on the clothes. And don't forget eye protection. My experience is that aluminum normally is worse than steel if it gets imbedded in skin or elsewhere. The body definitely knows its foreign and reacts accordingly.

Also good idea on the wax as a lube/coolant. Often overlooked but works well. Good lube for drilling also. Jam the bit into the wax, drill, and repeat as necessary.

Go

 

[MarkE]

Looks like it might be time to punt on this project.

I really don't have enough confidence in my abilities to try doing this with the tools I have at my disposal. So I spent the better part of the last two days trying to find a machine shop willing to do it for me. I found one place in Raleigh that said "sure, bring it in." But when I got there and he looked it over, he told me he didn't really have a way to get it done as accurately as it needs to be. He sent me to another shop that has the right cnc machines to get it done. Drove to the second place and it was some little shack looking place and no one was anywhere to be found. So, that was three hours of my life I'll never get back.

Got back home and made a few more calls. Found a shop in Garner that was willing to take a look. I sent him some pictures and a description of the work. He sent me back an estimate for $425, and wouldn't be able to work on it until the end of January. Not ready to pay $425 to modify a $99 router plate.

I also talked with Incra (makers of the plate I want to use) and they don't have the equipment to do custom machining. Same with MLCS.

Looks like I will probably end up using the lift with it's original plate. Just have to figure out how I want to mount the lift in my table, the plates are slightly different sizes and the new plate has a lip on the underside so the mounting ledge has to be a little more precise.

Bummed.

 

[Mike Davis]

Mark,
send your photos and specs to Kevin Mallot at Custom Machining in Colfax, NC.
You will have to call to get his e-mail since it has changed since the card I have was printed.

his number is 336-996-0855

i have never taken anything to him that he could not do and he should be much more resonable on the price.

However that work may be so involved that it is more expensive than the plate.

it would also help if you had the CAD work done.

 

[MarkE]

I did figure that that the machining costs would be higher than the price of the plate, just didn't realize it would be as high as that quote.

I am going to mess around with this over the weekend. I can practice making templates in hardboard until I get everything aligned properly, then try to figure out the best way to do the machining. If I can't get get the aligment set to my satisfaction, I'll just go ahead and use the lift as is.

 

[DaveD]

Can you sandwich the two router plates together? You will lose the thickness of the manga lock plate in router height adjustability though.
You may also have to trim the width and length of the pictured plate so it will fit in hrough the hole in the router table. However that would prevent you from ever using it as originally intended.

Alternatively...

If you drill the blind tapped holes all the way through you could then use an appropriate sized bolt, with a ground point on the end to indicate centers on the new plate.

Is there a dimple in the center of the ¾" and 1-¼" holes you could use as center alignment holes by drilling them out?

Probably the 3 very critical dimensions are the 3 recesses because they probably align the rods the router travels on and the height adjusting rod.

How thick is the magna lock plate and how deep are those 3 recesses?
How critical is that big center hole? Will it just be a clearance hole or does it need to also be precise with the tabs and recess lip on the bottom?

Can you post a picture of the router lift face that mounts up to the plate? I'm interested in seeing how the rods specifically interface to the bottom of the plate.

 

[striker]

Just a stupid question here.....you mention magnetic inserts in the OP and we're talking about a aluminum plate ?? I assume there's more to it than I'm understanding..

FWIW- If your not familiar with doing this kind of work I'd suggest finding someone with a Bridgeport. With just your basic shop tools you're going to be hard pressed to come out with the precision this likely requires.

 

[MarkE]

Can you sandwich the two router plates together? You will lose the thickness of the manga lock plate in router height adjustability though.
You may also have to trim the width and length of the pictured plate so it will fit in hrough the hole in the router table. However that would prevent you from ever using it as originally intended.

Alternatively...

If you drill the blind tapped holes all the way through you could then use an appropriate sized bolt, with a ground point on the end to indicate centers on the new plate.

Is there a dimple in the center of the ¾" and 1-¼" holes you could use as center alignment holes by drilling them out?

Probably the 3 very critical dimensions are the 3 recesses because they probably align the rods the router travels on and the height adjusting rod.

How thick is the magna lock plate and how deep are those 3 recesses?
How critical is that big center hole? Will it just be a clearance hole or does it need to also be precise with the tabs and recess lip on the bottom?

Can you post a picture of the router lift face that mounts up to the plate? I'm interested in seeing how the rods specifically interface to the bottom of the plate.

I am trying to preserve the original plate just in case my efforts in machining a new one don't work out. That pretty much prevents the stacking approach and drilling through the blind holes.
The center hole is where the inserts mount, it is already there on the replacement plate. All of the other holes that need to be made need to be indexed around the center hole so that the router will be centered under that hole when it is mounted in the lift.

Here is the original plate:


This is the lift sitting where it mounts to the bottom of the plate:

Just a stupid question here.....you mention magnetic inserts in the OP and we're talking about a aluminum plate ?? I assume there's more to it than I'm understanding..

FWIW- If your not familiar with doing this kind of work I'd suggest finding someone with a Bridgeport. With just your basic shop tools you're going to be hard pressed to come out with the precision this likely requires.

The plate is aluminum. The top of the plate has 4 recesses machined around the center hole where magnets are screwed in with small allen screws. The inserts for the plate are steel and they have holes in the tabs that sit over the magnets so that the insert can be adjusted flush with the plate while the insert is in place.



So, I spent some time working on this today and I think I am making some progress. I was able to make a pretty accurate template from 1/4" hardboard. Only took two attempts. I've got the large hole locations laid out on the bottom of the Incra plate. I will lose one threaded hole that was there for a starting pin. I can drill and tap another one if needed down the road.



I found an old aluminum plate out in the shop and was able to experiment with some carbide forstner bits. They cut the aluminum just fine. Once I get the large holes drilled to the proper depth, I can put the lift on/in the plate and use the holes in the lifts mounting pads to locate the rest of the mounting hole locations.

As far as tapping the blind holes, I'll use a standard tap to get the threads as deep as they will go. I can then use a hardened screw to make the last few threads in the bottom. If that doesn't work, I'll just drill the holes through and counter sink the exit holes in the top a bit.

Hope this all works, if not, I will only have ruined one router plate and wasted a bunch of time.

 

[nn4jw]

Mark, seems like a bottom tap is what you need for those non-through holes. They aren't really any more expensive than regular taps, just different.

 

[toolman]

Mark, use WD-45 or a lite oil will work for your coolant, it works good on Alum. and if you can drill thru on the tap holes it will be easier than blind hole taping.