Help need with Drill jig

Alan,

Little has been said so far about how your plastic bits fit together and interact with each other.

Are you using pins to fit in the respective holes? Is it fastened with screws, self tap or otherwise?

How many holes in each member wil be populated? All this has a bearing on the accuracy of positioning of the holes in the plastic and likewise on the type of jig you require.

Note that those press fit serrated bushes you highlighted are only to 0.003" concentricity so you're off to a poor start there if you a looking to use close fitting pins in the assembly.

As for jig design there will be many ways of constructing but I would consider locating the parts against dowel pins (2 on one edge and 1on the end) as this will enable swarf from your drilling to be kept clear of the register faces and minimise the chance of swarf accidentallly mis-locating your parts and subsequent holes. At 100 off it matters little whether you go MS and hard bushes or gauge plate but I would try and incorporate a toggle clamp to keep your part in register whilst all the holes are being drilled

Bob D

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0.003mm so 0.0001181 " [ approx] which is probably a tad better than the average bench drill or POS Bridgeport.

John S.

John S,

Sorry mate , Go and read the PDF file for those parts B&T are so long established they still have imperial sizes.

I tried to copy the page to you but its a bit to big for this system

**LINK**

They are for use in plastic jigs and composite materials rather than "real "engineering materials

Bob D

Gauge plate would be about the best for your needs, also no need to harden it.

Ah yes 3 microns, a tad better than a Bridgeport, agreed, but also about 30 times better than anything Mr Chinaman can produce.

Donald.

Bob,

My apologies didn't follow it up.

Mind you just how accurate can you get the holes ? Recently just done some parts for a company that makes CCM machines, nothing critical but took a lot of care to get the holes bang on using a quite new DRO system.

As a favour they put it on one of their machines and non of the 12 or so holes was to the drawing.

Quite an eye opener when you think you are doing well and the results show you are not.

But how many are in the same boat given they cannot affort a CCM report on all their parts ?

John S.

Ok, a some more information on the box im trying to construct.

The 2 pieces come together like below. The angled piece is the side, and the part at the end is the end cap. There would of course be another angled piece, and end cap, but this is just so you can visualise how they join up. There are 2 height boxes im planning, a 100mm high which has 2 joining holes. 150mm high, which has 5 joining holes. The parts are to be joined together with M3 screws.

I just need to get consistent holes drilled so that the parts are interchangeable.

Alan,

Thanks for added info.

Why are you only drilling 2.5mm? Are you expecting the M3 screws to tighten the box assembly?

If so you would be better drilling 3mm clear in one face and 2.5mm in the end face. Using self cutting screws for plastic you can then let the screw pull the assembly tight. It will not do that if both parts are having the thread cut in them.

Be aware that with plastic assemblies there will always be a finite limit to the number of times you can tinghten and unscrew before the thread fails so intercchangeability may be impaired.

I admit to being confused by how changing from 100mm to 150mm got you 3 extra holes to use!

Bob D

Sorry i ment 3 holes at 100mm. I understand that the plastic isnt going to last, they dont get changed around too much. I just need the option to change if needed, and that all the parts will fit. The plastic can be replaced easily enough. this is why i want the jig, so the holes can be remade with ease.

Regards,

Alan

This is all now sorted with a massive thanks to John and his black and decker :P

Thanks to everyone for there help and input.

Alan

Edited By Alan Crookes on 28/11/2012 23:07:17

If you wanted the threaded holes to last, or need to repare them in the future, little threaded inserts are easily fitted in the holes. Ian S C

Does anyone have a 'size 2 Reliance Drill Grinding Jig' ? I want to make a replica - I have both No 1 & No 3. but I need to know what its dimensions are - all 3 were to the same proportions. just the dimensions of vee drill tray is enough.

Just out of curiosity, what are the boxes for?

Edited By Hopper on 12/09/2017 08:53:26

The boxes are to store the fifth anniversary cards of this thread resurrection in

Dear Peter,

I have a Reliance Drill Grinding Jig and it is great. I am not sure if it is no. 2 as the box is long gone. I have also sharpened drills considerably smaller than 1/4", but it looks exactly like the illustration of the no. 2 jig.

The trough is 15 mm from the centre of the V to the edge (up the inside side of the V) and the trough is 70 mm long. The trough spindle extends this to 125 mm.

I couldn't see how to attach a file to this post, but if you wish I could email a PDF to you of the instruction manual. It does not give dimensions unfortunately, but pictures the item and illustrates how to use the item very well.

David

Doh!!! Caught again.

Perhaps the MODS can carve the last query re drill sharpening jig and subsequent answer off and start a new thread to save confusion. Sounds like an interesting project (the sharpening jig, not the ancient plastic boxes!)