Thread: Here we go again . . . MK4
The first plate has now been drill and counterbored:
The second one is cut out:
Spotted and ready for drilling:
The DRO I fitted to the pillar drill works really well for CBs. Although the depth is not critical, it looks nice if they are about the same height as each other. These are the CBs for the M6 bolts, drilled to a depth of 10mm as the thread needs to stick out to get good engagement:
All the top holes are now finished. Then onto a light sanding with well used paper, then green scouring pad to remove the scratches and after about a minutes work they look quite nice:
Another dry assembly fit:
Next job is the tapped holes in the sides. I bought one of these precision vices a while back to hold the work on it's side:
Mine is the second from the top - Precision Tool Vice Type 2 - 90mm wide
But I need to make some special clamps to fit into the groove. Here is some 10mm plate roughly marked out. I should get 4 clamps out of this strip. I'll put the usual stepped clamp triangles under the far end of each clamp initially, but may add a packer piece of the right height instead to make setting up quicker.
Last edited by routercnc; 15-05-2016 at 10:25 PM. Reason: pictures fixed
Slight change of plan. I decided to use the 10mm plate to make a nice set of clamps to replace the quickly made scrappy ones. I've been using odd bits of aluminium plate that were supposed to be 'temporary' but ended up being used for ages.
There is no hard and fast rule for the dimensions but here was mine:
Here are the 4 small clamps I made out of that 10mm plate:
The came out pretty well.
Now I'm using those clamps to hold the workpiece for the precision vice clamps:
Here is the drawing for them:
Here is one roughed out as a trial:
Looks like it will work OK:
Just need a set of 4, then I can use the vice to machine the holes in the side of the plates.
Anyone else made their own clamps for machining, especially if they have any extra / time saving / novel features ?
Nice looking clamps! I'm about to change the way I cut the kits for eBay, instead of using masking tape to hold them down on the bed I'm going to cut out the 915mm x 102mm (by whatever depth the balsa is, 1.6 & 2.4mm) out of a piece of MDF and then using a cutter twice the diameter I normally use (2mm in this case) rout out 1mm deep the programming so that when I cut the wing ribs or fuselage sides I can send the cutter up to 1mm below the wood to ensure I cut all the way through. I'll be making holding clamps (sorry about all the waffle to lead up to the clamps I'm going to be making!!!) the same shape as single servo horns which I can swivel over the balsa to hold it...going to use some scrap 4mm Ali I've got lying around...hope that makes sense? :)
Last edited by njhussey; 20-05-2016 at 08:27 PM.Neil...
Nice work on the clamps, always handy to have.
Some solid blocks from the side may come in handy for you, seen in this video:
Last edited by Lee Roberts; 21-05-2016 at 05:59 PM..Me
OK, to conclude making the precision vice clamps.
Here is the first one set up against a backstop datum (a parallel), with the top surface flush with the jaw (using another parallel to get it level - not in photo). This is so I could batch machine the 4 parts without having to zero and set each one up:
By chance the long clamps I'd just made fitted into the slots on the side of the vice so I could hold it down to make the proper parts. For info the slots in the vice are 10mm wide.
I profiled the counterbores rather than using the drill press:
Then the clearance hole. I don't like drilling deep holes with an end mill as they can jam up, but because of the counterbore they were quite shallow and there was no problem:
Because of the datum plate on the vice each one took moments to set up, then a few minutes on the counterbore and hole and job done. Cleaned up the holes and finished:
OK, now back to the main project. I dialled in the fixed jaw of the vice:
I needed to drill holes in the edge of the plate so I used the back face of the fixed jaw to clamp to:
Here is the backstop datum so the second plate would drop in without having to zero:
Then I offered up the parts and the holes were in perfect alignment (lower 5 holes in the plate). All was going well and I was really beginning to like this new vice! :
Then I noticed a problem. The outer plate is clearance for an M8, and the end plate I'd just drilled/milled should be M8 tapped which is dia6.8. Clearly they were the same size.
I checked the CAM and realised I'd picked the outer dia for the M8 tapped hole, which is 8mm. The inner circle, then one I wanted, is 6.8mm. This is because originally they were CAMmed for drill holes (so it doesn't matter which circle you pick), but at the last minute I decided to mill with a 6mm carbide to 6.8mm to save drilling out. But I didn't change the geometry so they were milled to 8mm. Aargh!!
OK, what to do!! M10 x 1.5 takes an 8.5mm pilot so I've ordered M10 button head bolts and will tap to M10 instead of M8. My M10 tap was from a car boot sale and did not want to cut so I've ordered an M10 tap from the same place I bought the M8. It is a spiral fluted tap and the last one I bought from them cuts really well and is good quality.
So I need to wait before I can assemble the end plates.
The other problem I had today was going too deep with a 6mm spot drill which clogged it up and jammed, then snapped it off in the part ! My fault for pushing it too far. Now I need to get a carbide cutting removal tool as someone posted in my thread a while back when I broke a tap.
Sorry to read about the problems, all part of the fun...I think? Lol
On a positive note, you've got this as the money shot though a:
They look nice and look to be doing the job just right too, nice job
Update time. It soaked up many hours to get back on track. After a lot of prodding with any pointy shaped tool I could find, plus a soak in WD40, I manage to lever the broken spot drill out of the hole. The edge of the hole was a bit damaged where I'd levered against it but at least the hole was clear.
After checking the main part of the hole was still in alignment I bored it out from the 6mm spot size to the 6.8mm pilot, then ran the M8 tap into it. I had to give it a generous countersink to tidy up the damaged surface then all was well again.
I also managed to drill and tap out all the holes in the bottom of the outer edge from dia8 (should have been 6.8 for an M8!) to pilot 8.5 and then used my new M10 spiral flute tap. As per my recent M8 tap this is also a RotoGrip tap and is very sharp and cuts really well. This one was £11.03, which sounds a lot vs the cheap ones but I think it is worth it having used both.
Here is the ebay link:
In case the link expires in the future here is the description:
HSS Ground Machine Tap Spiral Flute M10 x 1.5 Quality Made by Volkel. Germany
The button head M10 cap heads had also arrived so I was able to trial fit those. All looking good:
Next job was to cut the RHS steel beams to size. I was going to mark it out and use the thin grinding wheel on the grinder to cut it but after lots of deliberation decided it was time for a new tool. In the end I went for this one which is the 355mm rage2 saw. This is because it can cut up to 120mm x 120mm which should cover all needs. It has a nice soft start and just drops through the steel with ease. It is also pretty square out of the box - helped by just having a pivot and no slides etc.
The first beam was cut out and offered up. Looks OK. It is about 0.5mm short of the 730mm length as drawn to make sure I could set the end pieces the exact distance apart.
Next I need to cut the 2nd beam to length then I'm thinking about the best way to set the ends the correct distance apart. Current thoughts are to maybe use the CNC machine to drill out the holes at each end in the side of the RHS beam, including a special hole for a hardened dowel locator pin at the far end. There would be a matching locator hole in the triangular brace side plate at the far end to push the dowel through. This should set the far end housing a set distance from the near end housing.
Another option, is to CNC machine 2 shallow pockets into a large sheet of plywood to take the 'footprint' of each end housing and set them the correct distance apart plus have them squared relative to each other. I could just use a tape measure and square but feel like an assembly jig / guide would be nice. Any other thoughts?
That's looking good now, coming along nicely! Sad I know....but I do like to see lots of shiny metal with lots of holes drilled in....note to self, must get out moreNeil...
The Following User Says Thank You to njhussey For This Useful Post:
Second beam cut to length using the first beam as a guide:
Decided to use the CNC machine to drill the holes. Here is one of the beams clamped down and being dialled in. Obviously the edge is not very straight but I wanted to get it fairly close:
6 holes at each end drilled and then milled to 6.8mm, plus a 6mm dowel pin hole at the far end:
Then onto the tapping to M8:
Yes I know, ended up with holes a bit close to the edge - they were covered by another part in CAD and did not realised I put them so close to the edge. Will still work, but could have been better.
Then a trial fit. Note that only the front beam has holes in, and these are only in one side. Still lots to do on these bits. It all fits and aligns well but as I suspected would happen when the bolts are tightened it lifts/rotates one end of the gantry about 0.5mm from the flat plane. This is because the RHS is not perfectly flat along the lengths and so the ends are forced to align with the sides of the RHS.
I intend to machine just enough on each edge of each face to get it all square. This could be just the outer 3-6mm or so as I'm hoping the raised bits are on the edge / corners so just knocking these back a bit will create surfaces which are in plane with each other and square. I think that when I tighten the bolts the membrane flat parts will pull up tight to these new surfaces on each edge and everything will be square again.
I don't want to machine to whole surface as this will make the part quite a bit smaller. We'll see how it goes and then I'll repeat on the other one. Maybe should have done this before the holes . . .
but until it was pulled up tight I didnt know how much it would move.
Anyway then I'll take off the triangular corner plate at the far end and machine in a matching dowel pin hole which will allow me to get the ends the right distance apart from each other.
Actually on this note I noticed that the 6mm end mill I used to drill the 6mm dowel pin hole in the RHS actually made a slightly larger hole. Putting a 6mm shank in there showed it to be a loose fit. I suspect the runout in the chinese spindle may be adding 0.05mm all round so 0.1mm larger diameter? If so I'll use a smaller end mill and interpolate the hole but creep up on the fit.