New Minigraf 4 User: Some advice please

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New Minigraf 4 User: Some advice please

Postby millieri » Tue Jun 05, 2018 6:15 pm

Afternoon All

Having used a Cassese CS79 for a few years, I thought I would make the leap to using a pneumatic underpinner. The CS79 could produce good joints but not consistently (in my hands at least).

I saw a used Minigraf 4 for sale and made a long round trip to collect it. My excitement about using it has been dampened as I'm now producing inferior joints to my old machine. The Minigraf seems to be working ok however; there are no air leaks and the parts appear to move correctly.

Given the popularity of the Minigraf 4, I know it must be something that I'm doing wrong and I'd like to ask experienced users for some advice.

One of the main issues I'm having is that when I move the driver head from the back position to the front (it's the 2P model), it sometimes drags the moulding with it. I've attached a link for a video showing this:

https://vimeo.com/273547361

Even when this doesn't happen, I'm still not producing consistently tight joints (see photos).

This particular moulding is quite a soft wood. I'm using 10mm wedges that were included with the sale of the underpinner; it's not stated on the box whether these are for soft or hard wood. Are these wedges the same as the newer ones made by Alfamacchine?

Any suggestions or advice would be gratefully received.

IMG_5844.JPG
IMG_5844.JPG (2.67 MiB) Viewed 1429 times

IMG_5845.JPG
IMG_5845.JPG (1.79 MiB) Viewed 1429 times

IMG_5846.JPG
IMG_5846.JPG (2.17 MiB) Viewed 1429 times
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Re: New Minigraf 4 User: Some advice please

Postby Framemaker Richard » Tue Jun 05, 2018 6:54 pm

A few things come to mind.. can you post a photo showing the back of the frame join?

the catching of the block causing it to drag the corner with it, could be that the wedge is not be fully driven into the wood. The hammer on the minigraf has a small raised section that causes the underpinner wedge to be driven a tiny way below the wood surface, this raised part of the hammer does wear away eventually and means a replacement part is needed..

I find that when I move to the second position it is best to fully release the top clamp (foot completely off the pedal) and then insert the second pin.

The V nails look like normal wood to me.
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Re: New Minigraf 4 User: Some advice please

Postby Abacus » Tue Jun 05, 2018 6:55 pm

Although I don't have any experience of the minigraf the following thought occur to me

1) why isn't the inner clamp operating (the clamp that is nearest you when you are pinning, which closes up the joint prior to the pins being inserted)

2) I wonder if the pressure is sufficient, perhaps after inserting the first pin, it is still a little proud and this drags the moulding when the carriage moves, or

3) have you got the pins in the right way up? (Glue up?)

Are the pins fully in the moulding? Or slightly proud?
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Re: New Minigraf 4 User: Some advice please

Postby prospero » Tue Jun 05, 2018 6:59 pm

Never used a Minigraf but....

Going by the picture my first thought would be are the nails loaded the right way up.

Second thought - insufficient top clamping pressure.


Just a thought. :)
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Re: New Minigraf 4 User: Some advice please

Postby Mark Thornton » Tue Jun 05, 2018 7:38 pm

That Minigraf has been tampered with, the wedge load cylinder should not jump back and forth when you press the pedal and the rebate clamp isn't working at all which indicates someone has re-piped the valves the wrong way round.

Also (as Prospero said) do you have the wedges the correct way up? It should be the side with the glue on facing upwards.

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Re: New Minigraf 4 User: Some advice please

Postby millieri » Tue Jun 05, 2018 10:36 pm

Thank you for all your replies. I went from Richard's with some hope of some things to try out until I saw Mark's post!

Richard: I will get another photo in the morning.

I will check the wedges are correctly loaded, as I didn't actually load them, it was the seller.

Mark: is it possible for me to sort the issues with the piping out, or does it require more expert attention?

Thanks again.
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Re: New Minigraf 4 User: Some advice please

Postby millieri » Tue Jun 05, 2018 10:42 pm

Actually, I've just watched the video that I posted and I can see how I've caused confusion about the rebate clamp; apologies. Basically, I'm not pressing the the foot pedal at all. I'm just using the lever ('special lever' according to the manual) to change the wedge position. What I was trying to demonstrate was how the moulding is being moved when the wedge position changes.

Prospero, would you say I should be moving the top clamp closer to the moulding?
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Re: New Minigraf 4 User: Some advice please

Postby theframer » Tue Jun 05, 2018 10:52 pm

Looks like the block is to high and is catching the moulding?
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Re: New Minigraf 4 User: Some advice please

Postby millieri » Wed Jun 06, 2018 9:01 am

@theframer Yes, that's definitely a possibility but I'm not sure how to lower the block?
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Re: New Minigraf 4 User: Some advice please

Postby millieri » Wed Jun 06, 2018 10:06 am

:Slap:

It's amazing what using the machine as it was intended can do.

Firstly, the wedges were the wrong way around.

I also moved the top clamp closer to the moulding as advised.

I've just knocked up a quick frame and the problem with the moulding being dragged now seems to have been eliminated as well. I would say there is a definite improvement in the join but I rushed my cuts slightly so I think they can be improved.

The felt on the pads I've got is a quite worn. Do you use felt when replacing it or has anybody tried using something like rubber more like the Cassese pads?

Thank you to the sage advice of the forum; I don't know what I would do without it.

I'll post back with an update when I've done a bit more work with it.
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Re: New Minigraf 4 User: Some advice please

Postby prospero » Wed Jun 06, 2018 11:05 am

:D

The thing with pneumatic underpinners is that you don't get the feedback though your leg as you would with the CS-79.
You can't really get that 'feel' that tells you it's got a good join. The Minigraf is an excellent machine, but like all machines
you need to get to know it to get the best results.


A good material for pressure pads is cork. Not sure if you can still get cork floor/wall tiles but that's the sort of thing.
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Re: New Minigraf 4 User: Some advice please

Postby millieri » Wed Jun 06, 2018 12:58 pm

Thanks Prospero. As it happens, I do have some spare cork tiles kicking around.

The person who I learnt a bit of framing from, who is now sadly retired and I've lost contact with him, used to swear by manual underpinners and always discouraged me from getting an air powered machine. I think the CS79 is a great machine but it has no clamp so there's always the possibility for a little bit of movement even if you think you've gripped it as tightly as you can.
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Re: New Minigraf 4 User: Some advice please

Postby prospero » Wed Jun 06, 2018 5:17 pm

I've never used a clamp. I have very virile thumbs. :P

The v-nails are in effect internal clamps. As long as you can hold the two pieces still while they go in the jobs a good'un. :D

The thing about manual pinners is the simplicity. Lots of things can go wrong with a bells'n'whistles machine. I won't say my
machine has never thrown a wobbly or two but nothing I can't cure with a hammer. It's been performing well since I got it new in 1984. :clap:
You don't get that satisfying hisss-clunk sound, but I have learned to live with that. :roll:
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Re: New Minigraf 4 User: Some advice please

Postby millieri » Thu Jun 07, 2018 12:25 am

Yes, the hiss clunk sound is rapidly becoming quite a satisfying sound to me. I'm obviously still adapting to the more automated underpinner. My joints still aren't there yet. What's confusing is that with a manual underpinner, you can work out where you might have gone wrong if your joints aren't great, but with the pneumatic machines, there seems to be so many more variables.
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Re: New Minigraf 4 User: Some advice please

Postby upload » Wed Jun 13, 2018 8:30 am

Had the exact same problem on my minigraf 4 , hard wood wedges used on softwood.. changed wedges to SW , perfect join ..
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Re: New Minigraf 4 User: Some advice please

Postby kuduframes » Wed Jun 13, 2018 9:47 am

I've just read through this post for the first time, couple of comments which may be of use to you -
Lion do replacement felt pads 317 for the L shape and 3024 round, they also supply the new style head which takes different hardness polymer pad, see 9462/3/4/5. Not cheap but I think worthwhile, I only have the blue pad, 9463 it's very good to use for most finished mouldings as it tend not to slip as the felt pad sometimes can and is soft enough not to mark even a delicate moulding.
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Re: New Minigraf 4 User: Some advice please

Postby millieri » Thu Jun 14, 2018 11:49 am

Many thanks for the updated information. Yes, I've now seen the replacement pads for the minigraf. They look good and I might have to invest in them.

Regarding the photograph above of the wedges I'm using, Richard stated that they look like those for normal wood. Upload: are yours different to these ones?
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Re: New Minigraf 4 User: Some advice please

Postby kuduframes » Thu Jun 14, 2018 5:47 pm

I almost passed a comment about the photo of the wedges, they don't look like the usual PTM wedges that are supplied by Lion. I'm not suggesting that they are not genuine, maybe an older design ? If your problem persists I would be tempted to buy a new box of normal softwood wedges, Lion 832 is the 10mm normal wedge.
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Re: New Minigraf 4 User: Some advice please

Postby millieri » Fri Jun 15, 2018 4:10 pm

Thanks Kudu. I think my wedges are quite old. The guy I purchased the Minigraf from had had them lying around for ages. I'm using them just as he gave me so many.

This morning I pinned my first oak frame and it wasn't good; corners with gaps not pulled very tight! I'd tried a test piece first. Double stacking the wedges was a disaster as the second wedge was just pushed behind the first, not underneath. Had to resort to leaving it in a strap clamp and then sanding a bit of sawdust into the gaps while the glue was setting.

Should I expect to get a good joint in oak with the underpinner only?
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Re: New Minigraf 4 User: Some advice please

Postby Framemaker Richard » Fri Jun 15, 2018 4:15 pm

I would never stack wedges in oak, I use normal wedges and corners come out good on a minigraf 4 most of the time, the exception being if it's a particularly hard section of timber. Also with wedge position on oak (depending on the actual width of the moulding) I would not go near the back edge as this will often push the back apart or cause a pin to come out the back.

I turn up the pressure on the gauge to about 150/175 for oak, from 100 for normal timber like obeche.
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