Chinese draft angles

I am mounting 2 XSY-AT1 VFD's using the 5mm bolt holes provided.

I measure them with my new 200mm dial caliper.

I drill them using 5 micron DRO scales for precise location.

I go to insert a bolt and it doesn't fit. No room for the head.

Curses, foiled again

(I didn't mean to start a new chapter in the tea room, get it right next time maybe, Sorry!).

Edited By Robin on 12/10/2022 17:19:21

That is an annoying problem. I presume you are fixing it to a bench, so why not grind the heads of your bolts to fit the machine, and then put nuts and washers on from underneath.

Just a thought.

Rob

They are clearly clearance holes for M3 plus a large washer

Martin C

I go to insert a bolt and it doesn't fit. No room for the head.

Maybe use a screw? Apart from possible errors with the new dial caliper or diameter selection?  Which bit of the process are we talking about?

Thoroughly amazing that they did not come predrilled properly.

VFDs, btw, should be mounted inside a suitable electrical enclosure, not screwed to anything flammable. Likely all in the installation instructions…. But perhaps you are only sitting them on the bench at the moment

Edited By not done it yet on 12/10/2022 17:53:42

I have already painted myself into a corner.

Luckily I spotted a liana hanging from a light fitting. This allowed me to swing up, Tarzan style, to get this aerial picture...

Try cap head screws.

Perhaps tap the holes, and fix from t'other side - to a sub-plate if no access from that side for fixing to whatever.

One wonders how stuff can leave the factory with such howlers...

I think its a bit unfair to blame the Chinese for this! The HuanYang inverters are a low cost commodity item and not perfect although the hole location is a bit of a howler. I can see also that if you have carefully prepared tapped holes than getting any standard M5 fixing is going to be a bit challenging. Judging from the picture I would say that if you reduced a slotted or Pozi head to 5.60mm diameter it would do the job.

I have an expensive set of British made cast iron, machined all over (apart from the slots/holes) angle plates. A large proportion of the slots lengths are unusable because of the fillet between the internal faces. I cannot get to take a picture just now but have grabbed this picture off Google images that shows exactly (Well its 45 degree fillet on my plates but you get the idea).

I see the same sort of out of proportion features, like massively wide slots on many pieces of workshop tooling and workholding items like lathe faceplates and machine vises.

Ian P

If you don’t mind my mentioning this, Robin

That hole appears to be ‘wrong’ in more than one way

Aside from the position, it appears to be oval

Are they all similar, and similarly orientated, or has each been ‘dragged’ differently ?

… How did you decide which ‘centres’ to measure ?

.

.

MichaelG.

The holes are round.

Viewed from below there is a strange slot next to each mounting hole, possibly a mould opening fix which displaced it.

I think I may have to make up some kind of counterbore to make way for a reduced bolt head. I have been playing with burrs in my Dremel but I am not very good at the arty farty, freehand stuff

.

Then count me “astonished’ by what I see in your photo

… I only had a small glass of Talisker

MichaelG.

Me too - it certainly looks like it's been "drawn"
.

A 5mm hole is not meant for a 5mm bolt. It's a clearance hole. As Martin said above, 3mm screws with washers and nuts would do the job just fine in such a light-duty application. Or the electrician's favourite: zip ties.

There used to be BS standards and the like specifying the amount of clearance around bolt holes to allow for the hexagons plus spanners, but obviously a thing of the past.

.

Many a true word, said in jest

MichaelG.

So it is a design or manufacture flaw, but if we are going to moan about small errors why is this thread called 'draw angle' when that is not the issue?

+1

Very true

Ian P

Hi

It is called draft angles because I thought that was the problem in the mould before I spotted the rectangular cut-out next to the 5mm bolt hole. Looks like a puller to me

Ever since I discovered zero backlash screws, DRO readouts and amazingly cheap precision measuring tools I have delighted in drilling holes exactly where holes need to be. When I see 5mm holes like these I drill for 5mm bolts and it is wonderful when it all goes together like it never did before. This is what makes it fun for me

A hole too close for the bolt head: a school-boy error, which we all make from time to time !

Use a side cutting tool bit* and 'slot' the holes diagonally out towards the corners, keeping the width of the slot the same as the diameter you require, but thus allowing room for the bolt head and a washer.

(@MG: The picture of the bolt hole might look oval, but that is almost certainly owing to the distortion caused by the wide angle lens of the camera and the angle the shot was taken from.)

*I don't know the correct term.

Edited By John Doe 2 on 13/10/2022 10:14:43

Why would you use a fixing that would fill the slot? Smaller diameter bolts not only don’t wedge

but allow for some sideways adjustment when setting up, turning up some hefty thick washers is the name

of the game.

regards Martin

I think the bolt on the top row second from left would be just what is needed for this job. I think the cap screw suggested above would be worth a try.

Mike